This is all about the relationships Voldemort had in life, with both his followers and his enemies.
Tom Riddle grew up in a Muggle orphanage, not knowing any members of his family. His mother, Merope Gaunt, died shortly after giving birth, never attempting to save herself through magical or other means. His father's feelings toward him are unknown, as he fled then-pregnant Merope after she stopped drugging him with Love Potion, and didn't track down the whereabouts of their child thereafter. The two met face-to-face in 1943, when Riddle killed his father and paternal grandparents. Riddle was disgusted by his Muggle relatives, and took on the alias "Lord Voldemort" partly out of a desire to be rid of his “filthy Muggle father’s name”. Tom Riddle Jr viewed his father as abandoning his mother for being a witch. Whether this was due to a lack of information or Riddle's prejudice against Muggles is unknown.
Despite the maternal side of his family being direct descendants of the great Salazar Slytherin, Tom was unimpressed when he found his deranged uncle Morfin living in squalor at the Gaunt shack, and was not above framing Morfin for murder and stealing his maternal grandfather's prized heirloom ring. Even as a child, he showed contempt for his mother, and for the weakness of mortality, when he assumed Merope must have been a Muggle if she had been unable to survive.
Harry Potter became Voldemort’s mortal enemy after the Dark Lord heard part of a prophecy that foretold the birth of an individual destined to destroy him; two infants met the criteria, but for the simple reason that Harry was a half-blood like himself, Voldemort considered him more of a threat than Neville Longbottom. In targeting Harry, Voldemort unwittingly “marked him as his equal”, thus sowing the seeds of his own destruction. Because Harry’s mother willingly sacrificed herself for her son, the curse backfired. Voldemort lost his physical body, and unintentionally transferred some of his powers and abilities to Harry, while a piece of his soul embedded itself in a scar on Harry’s forehead, inadvertently making the boy a Horcrux.
Sybill Trelawney's prophecy stated that "The Chosen One" would have powers the Dark Lord lacked. That power is love, and Dumbledore realised that it was Harry's abilities, combined with his capacity to love, that would empower him to efeat Voldemort. Unlike Harry, who was mentally, emotionally, and spiritually intact and whose friends supported him out of loyalty and love (platonic affection), Voldemort was psychologically, spiritually, and emotionally shredded, feeling only arrogance, hate, greed, and jealousy; and he controlled his followers through fear, intimidation and coercion. Harry was disturbed to notice many similarities between them — they were both orphans who thought of Hogwarts as their first real homes, and both physically resembled their fathers, and to some degree each other. However, Dumbledore insisted that they differed in one absolutely crucial way — Harry had the ability to love, while Voldemort did not.
Voldemort became obsessed with Harry Potter after he failed to kill the one-year-old boy — livid that a helpless infant caused his downfall. He later sought revenge on Harry to prove that he, Voldemort, was the most feared and powerful wizard of all time. Voldemort's hatred and desire for revenge was strong enough that, when the horcrux contained in his diary encountered him in the Chamber of Secrets in 1993, he indicated that even the desire to kill muggle-borns in the name of Salazar Slytherin as his heir no longer mattered to him compared to trying to target Harry for several months since the start of the school year. Voldemort considered Harry weak in comparison to himself and he always discounted how love's power has aided Harry. But after possessing Harry's mind, Harry's overwhelming emotions for his friends and family were so overpowering and disturbing to Voldemort that they drove him out. He never attempted to possess Harry again.
When the two faced off for the last time, Harry urged Voldemort to feel remorse — the only known means of repairing a fractured soul — but Voldemort reacted with disdain. Harry went on to inform Voldemort that despite wielding the Elder Wand, he was not its master; Draco Malfoy won the wand's allegiance by disarming Dumbledore in the Astronomy Tower, but Harry had disarmed Draco months later. Thus, Harry was the true master of the Elder Wand. In his fury, Voldemort made one last attempt at Harry's life, but the Elder Wand was loyal to Harry, and the Killing Curse once again backfired on to Voldemort. Without his Horcruxes to sustain him, this time the curse finally and completely ended Voldemort's life. Voldemort and Harry were also related by blood, however distantly, through their shared descent from the Peverells (Voldemort through the Gaunts and Harry through the Potters). This made them distant cousins.
Ron Weasley and Hermione Granger
Though Voldemort never actually interacted with Ron or Hermione, he considered them his greatest enemies as well, because Ron, even though he was Pure-Blood, sided with half-bloods and muggle-borns, making him a blood-traitor to Voldemort, and Hermione because she was a muggle-born, and his belief was that muggle-borns should be wiped from the world.
It is unknown how Voldemort felt about his daughter since he died while she was still a baby. However, in the alternative timeline created by mistake by Scorpius and Albus, Voldemort had apparently put Delphi (known as the Augurey) in charge of the Ministry: Dolores Umbridge (Headmistress of Hogwarts in this timeline) constantly informs the Augurey with dispatches about everything that is going on in Hogwarts; the Augurey gives instructions to Draco Malfoy (Head of Magical Law Enforcement of the Ministry of Magic in this timeline), e.g. how to deal with incidents involving wizards killing Muggles and bribing the Muggle Prime Minister with gold in such cases. Some students in Hogwarts openly quote the Augurey's motto that "the future is ours to make", indicating that the Augurey was probably a famous and respected force and inspiring example in the wizarding world of this timeline.
It is therefore likely that had Voldemort lived, he would have considered her an exceptionally faithful servant, something like his right-hand minion or deputy, and given her more power than he usually allowed his Death Eaters. It's notable that in this alternative timeline Delphi has her own official symbol - the bird emblazoned in a fascistic manner - that is widely used in this world, just like the Dark Mark, the official symbol of Voldemort. In the office of Head of Magical Law Enforcement in the Ministry there are Augurey flags flying down with this symbol, while there are flags with Dark Mark in Hogwarts. None of the Death Eaters ever had their own individual symbols and none of them ever had individual titles or alias, having just a collective name for their group, while Delphi was operating under her personal and unique alias "the Augurey" in this timeline, rather than being known just as another top Death Eater.
It is not known why he wanted a child, as he did not feel a need for love and disliked the idea of becoming emotionally attached to anyone, and in addition desired immortality. However, he likely realised that his daughter could become a talented and useful servant, as Bellatrix was. It is also likely that he wished to preserve the Slytherin Bloodline, on account of Voldemort being the last remaining heir of Slytherin. He kept her birth a secret, most likely because it may have placed her in danger, since Voldemort was considered the most powerful and dangerous Dark wizard of the time
Delphi was curious about her parents, and wanted the chance to know them. She went to great lengths to meet and save her father, even meddling with time to create a future where he lived, which shows she had some love for him. After she was defeated by her cousin Draco Malfoy, Hermione Granger, Harry Potter and Ron Weasley, she begged for death instead of having to face the fact that she failed her father.
Tom Riddle met Albus Dumbledore at the age of eleven, when the Professor came to invite him to attend Hogwarts School of Witchcraft and Wizardry. Although initially suspicious of Dumbledore, he was at least somewhat impressed by Dumbledore's demonstration of magic. Tom was pleased to discover that he was a wizard, as it confirmed the suspicions he long had about being “special.” The boy disturbed Dumbledore, however, when he admitted to being able to hurt people who displeased him and being able to talk to snakes. Even as Tom became an extremely popular student among his peers and Professors at Hogwarts, Dumbledore remained wary of him, and kept a very close watch on him.
Riddle (then known as Voldemort) returned to Hogwarts years after graduating to request the Defence Against the Dark Arts position from Dumbledore, who had become the school's Headmaster. Suspecting that Voldemort's true intentions were far more sinister than he let on, Dumbledore refused him the position; the result of Dumbledore's refusal was not only that the position of DADA professor became "cursed," but it affirmed Dumbledore's complete refusal to bend to Voldemort's will.
Voldemort despised Dumbledore, not only for latter's continued opposition, but also because Dumbledore's belief in the triumphant power of love was something that both confused and disgusted Voldemort. Dumbledore was thought to be the only person Voldemort ever feared and one of the few people Voldemort was unable to intimidate, due to Dumbledore being the only wizard whose powers and skill could threaten that of Voldemort's. Dumbledore persisted on referring to him as "Voldemort" to others and addressing him as "Tom" in conversation, a subtle but steadfast refusal to allow Voldemort to dictate the terms of their relationship, and a trait that would later be inherited by Harry Potter. Dumbledore led the efforts against Voldemort in the First Wizarding War; over many years, Dumbledore gathered crucial information about Voldemort's past and passed it on to Harry Potter, who would essentially take Dumbledore's place as leader of the opposition in the Second Wizarding War.
In 1996, Dumbledore and Voldemort met face to face in the Ministry of Magic during the Battle of the Department of Mysteries, where Dumbledore addressed Voldemort as “Tom” and said it was foolish of him to come to the Ministry. Voldemort initiated a fierce duel with Dumbledore, during which he tried to murder both Dumbledore and Harry, but was unsuccessful; Dumbledore was able to overwhelm him, forcing him to possess Harry so Dumbledore would kill Harry out of desire to kill him. This too was unsuccessful as Harry was able to exorcise the Dark Lord from his body and mind by focusing on his intense feelings of grief over his godfather's death. Cornelius Fudge arrived at the Ministry just in time to see Voldemort escape with Bellatrix Lestrange, and was finally forced to acknowledge the truth of Voldemort's return
Following his failure to kill either Dumbledore or Harry at the ministry, Voldemort assigned Draco Malfoy to carry out Dumbledore's assassination. Dumbledore became aware of this plot, and addressed it by arranging his own death with Severus Snape. At the time of his death in 1997, Albus Dumbledore had fully equipped Harry Potter with the physical, mental and emotional tools he needed to defeat Voldemort once and for all in 1998. Later on, during his search for the Elder Wand, Voldemort broke into Dumbledore's tomb.
Both Voldemort and Dumbledore are pretty similar; both were half-blood, although Voldemort knew nothing about Hogwarts, until he was 11. Both were recognised as two of the best wizards to go to Hogwarts and were both Prefects and Head Boy. Both created and led their own causes (the Order of the Phoenix and the Death Eaters). Both were extremely powerful, although Voldemort does not know love. Both possessed the Elder Wand during their life and that both Dumbledore and Voldemort extremely believed in Severus Snape.
Bellatrix Lestrange was among Voldemort’s most loyal and trusted Death Eaters. She was entrusted with one of his Horcruxes, though kept unaware of what it really was. It was stored in her vault at Gringotts Bank. She was fanatically loyal to her master. After his first defeat in 1981, she did not join many of her fellow Death Eaters in denying their association with him. Instead, she proudly declared that she remained his most loyal servant and that he would surely return. She considered Azkaban a place where she could wait for him, rather than a prison.
Her obsession extended to her being in love with and sexually attracted to him. On at least one occasion, during a meeting of his Death Eaters at Malfoy Manor, her face flushed and her eyes welled up with tears when he praised her.
He did seem to consider her of greater importance than most of his other servants. At the conclusion of the Battle of the Department of Mysteries, he grabbed her and Apparated away with her; she was the sole Death Eater who he bothered to help. When she was killed by Molly Weasley during the Battle of Hogwarts, he was furious, and intended to avenge her death when Harry intervened.
Although Bellatrix was married to one of Voldemort's other Death Eaters, Rodolphus Lestrange, the union seemed to be nothing more than a business-like partnership. It was Voldemort to whom she spoke in a romantic manner. She was outraged by anyone showing him the slightest disrespect. When Harry Potter called him by his name in 1996, she became enraged, feeling that he was unworthy of speaking the name.
Unknown to nearly all, it would be revealed years later after their death that Bellatrix and Voldemort had in fact engaged in a sexual relationship, resulting in the birth of their daughter, Delphini, who years later threatened to upset the timeline to be with her father. As Voldemort believed that he could cheat death, through his Horcruxes, he probably did not feel a need to leave a child behind as an heir. It is highly likely that he used the relationship with Bellatrix as a way to reward her for her undying loyalty to him, and for her rather potent and notable successes as his most loyal lieutenant. However a reward seems unlikely considering Bellatrix's failures at the Ministry.
Because of his egotistical and self-centred nature, he might have also been pleased by Bellatrix's obsessive love for him. He may have considered the usefulness of Delphini in the idea of siring a lineage of lieutenants devoutly loyal to him through familial bonds, seeing them as extensions of his own power and authority, much like many kings and tyrants who procreated to expand and solidify their own power through blood ties. He may have also chosen Bellatrix as a mate due to her blood relations and thoroughly proven power as a witch, thus marking her as a potent genetic combination and fit for Voldemort who revelled in his own status and power. A mate of such fortitude and strength would certainly appeal to Voldemort's pathological need to expand his fame and reputation. Voldemort also may have seen Delphini as a way of extending the power of the Slytherin bloodline beyond himself as a way of further showcasing his and his family's might and to further terrorise his enemies with the idea of another Dark Lord ruling alongside him. Voldemort may also have been intellectually enthused or curious at the idea of a student with similar powers and potential as himself, highlighting his vanity and ego even further as he had had no living relatives whose powers he could compare his own to or to have learned from.
It is also possible that the conception of Delphini was unintentional as very little is known about her background.
It is rather ironic that Delphini held such strong affection and fascination for her father, a man who felt no love. The alternative timeline where Voldemort ruled shows that he would have considered Delphini (known as the Augurey in that universe) a faithful servant.
Severus Snape became a Death Eater in the First Wizarding War. He was extremely loyal to Voldemort until he realised that the Dark Lord planned to murder Lily Evans. Snape appealed to Albus Dumbledore, becoming a spy in exchange for her protection. From that point on, Snape used Occlumency to prevent the Dark Lord from discovering his true allegiance.
After Peter Pettigrew broke the Fidelius Charm cast by the Potters, Lily died and Voldemort disappeared; however, while Snape was unable to save Lily herself, his love for her allowed her son, Harry Potter, to survive. It was because Snape asked the Dark Lord to spare her life that Voldemort gave Lily the option to flee, thus making her death a willing sacrifice. Following the death of the Potters, Snape's loyalty did not waver, and he swore to protect Harry from the Dark Lord, honouring Lily's sacrifice.
When Voldemort was reborn and called his Death Eaters to him, Snape did not appear until two hours later. The Dark Lord was suspicious, and feared that Snape had abandoned his service. On Dumbledore's orders, Severus claimed that his delayed return had secured the Headmaster's continued trust. The Dark Lord questioned Snape extensively, and found all his answers satisfactory; Snape was then welcomed back to the inner circle.
Voldemort's trust in Snape was further cemented when the latter murdered Albus Dumbledore; the Dark Lord did not know that Dumbledore had previously arranged the assassination with Snape. Snape became the Dark Lord's most trusted advisor and was given the position of Hogwarts Headmaster after the fall of the Ministry of Magic. Unbeknownst to Voldemort, Snape continued to undermine him as much as possible, following Dumbledore's instructions.
When Minerva McGonagall began to coordinate the defences of Hogwarts Castle for the impending battle against Voldemort, Snape fled, and was summoned to the Shrieking Shack by his Master soon afterwards. Snape saw that the Dark Lord had cast special protection around Nagini, and attempted to leave the Shack to give Harry a message from Dumbledore (as Dumbledore had instructed Snape that, once Voldemort seemed to fear for the serpent's life, he was to tell Harry that Harry himself was Voldemort's seventh Horcrux, and therefore had to die) on the pretence that he would find Harry and ensure that he was killed by no hand other than Voldemort's own. Dismissing Snape's concerns, Voldemort noted that, since Albus Dumbledore's murder, Snape had become the true master of the Elder Wand. Voldemort ordered Nagini to kill Snape, and though he claimed he regretted the necessity of this action, he showed neither sadness nor concern for the loss of Snape's life. Harry, who had witnessed the scene and entered the room upon Voldemort's departure, approached Snape, who gave him several memories that both revealed his true allegiance and passed on Dumbledore's message. Snape's last words reflected his truest motives: he instructed Harry to look at him, so that he would die looking into the eyes Harry inherited from Lily Evans.
In his final duel against Voldemort, Harry revealed that Snape had been loyal to Dumbledore since Voldemort had targeted the Potters.
One of the possible reasons why Voldemort placed so much trust in Snape was due to their rather similar backgrounds. Both men were the only children of Muggle fathers and pure-blood mothers. Both men's fathers had nothing but hatred for their sons and wives—Voldemort's father had abandoned his wife when she was pregnant with their son, while Snape's father was abusive towards his wife Eileen and their young son. Both Riddle and Snape claimed greater identification with their maternal lineage than their paternal ancestry—the Gaunts and Prince family, respectively. Both men grew up in poverty—Voldemort grew up in an orphanage, while Snape lived in Spinner's End. In addition, both Voldemort and Snape were sorted into Slytherin, and were known for their intelligence. Both men had a passion for the Dark Arts and blood purity as childhood, and bestowed grandiose titles onto themselves (Riddle was known as Lord Voldemort, while Snape adopted the name the Half-Blood Prince). Both saw Hogwarts as sort of a real home as opposed to their default home. Voldemort may have seen him as a trusted Death Eater who shared the same hatred for his father as he had for his own. The only thing that differs between Voldemort and Snape's relationships with their fathers is murder; Voldemort had murdered his own father while Snape did not murder his.
However, there were differences between Snape and Voldemort. Snape had a secret love for Harry's mother, Lily, for all his life, which motivated him to defect from the Death Eaters and protect her son, Harry Potter after her death at Voldemort's hands. Voldemort, on the other hand, disregarded love as a weakness that was beyond his comprehension, and had allegiance to only himself. This had coincidentally led to his own undoing. Another difference was that Voldemort grew up completely unaware of the wizarding world until he was eleven, Snape had apparently already known by the time he was nine (likely due to the fact that his mother was a witch and, unlike Voldemort's mother, actually present in her son's childhood).
The Malfoy Family
Voldemort held Lucius Malfoy in high regard as one of his best henchmen. He entrusted his diary to Lucius, which, unbeknowst to him, was one of Voldemort's Horcruxes. He plants the diary in Ginny Weasley's cauldron, allowing Voldemort to possess Ginny.
Over time, Lucius Malfoy and his family began to lose Voldemort's favor, as Lucius failed to fulfill the tasks Voldemort gave him.
Other Death Eaters
Those called Death Eaters were a group of Dark Wizards and Witches that followed Voldemort, fighting as the upper echelon of his army during both the First and Second Wizarding Wars. However, Voldemort did not take kindly to failure or disloyalty from his servants, and he made sure those who had believed him dead and did not try to find him following his disappearance paid the price upon his return. When he summoned his Death Eaters to the Little Hangleton graveyard, after he regained his body, he tortured and questioned them before forgiving and allowing them back into his service.
Despite many of the Death Eaters claiming to be close to Voldemort, and Voldemort often referring to them as his "friends" and his "true family", the Dark Lord saw them as little more than dispensable servants. The few Death Eaters in whom Voldemort appeared to place any amount of genuine trust were Severus Snape, Lucius Malfoy, Peter Pettigrew, Bartemius Crouch Junior, Bellatrix, Rodolphus and Rabastan Lestrange, though as time passes, he lost trust in them due to constant failure or wavering trust.
Some of Lord Voldemort's first Death Eaters were Avery Snr., the Lestranges, Mulciber Snr., Nott, Rosier and Antonin Dolohov. Others were Walden Macnair, Corban Yaxley, Augustus Rookwood, Selwyn, Travers, Thorfinn Rowle, Alecto and Amycus Carrow, Gibbon, Crabbe Snr., Goyle Snr., Jugson, Avery Jr, Mulciber Jr, Igor Karkaroff, Evan Rosier and Wilkes.
Like Voldemort himself, many were not above denying any involvement in actions that could get them into trouble with the legal authorities of the magical community. Many were willing to switch their loyalties to avoid danger or punishment, rather than steadfastly supporting their presented views.
After Voldemort's first downfall: Avery, Jr claimed to have been under the Imperius Curse and avoided Azkaban but also didn't attempt to find his master. The Carrow siblings Amycus and Alecto did not attempt to find him. Given Amycus (at the very least)' cowardly nature, it is likely that at the very least he would have done all he could to avoid Azkaban. The Crabbe family, notably Crabbe Snr did not attempt to find him and avoided punishment when put on trial. Likewise the Goyle family, notably Goyle Snr did not attempt to find him and avoided punishment when put on trial. The Malfoy family, Lucius Malfoy in particular, did not attempt to find him and Lucius claimed he had been under the Imperius Curse. The Nott family, notably Mr. Nott also did not attempt to find him and avoided punishment when put on trial.
Other individuals who showed disloyalty were Igor Karkaroff who betrayed many of his former comrades to the Ministry in return for his freedom from Azkaban, and went on to become Headmaster of Durmstrang Institute. Though he was still a pure-blood supremacist and did not accept Muggle-borns into his school, Karkaroff fled following Voldemort's return and was consequently killed by Death Eaters in 1996. Peter Pettigrew joined Voldemort out of cowardice, but did not attempt to search for him following his first downfall, so he hid from his fellow Death Eaters in the form of the Weasley family pet rat Scabbers and only rejoined him when he was flushed out by Sirius Black who he framed for his own crimes. Walden Macnair claimed to have been under the Imperius Curse to avoid Azkaban and did not attempt to find Voldemort after his first downfall. Corban Yaxley managed to avoid Azkaban and did not attempt to find Voldemort after his downfall, believing him finished.
On the other hand the Lestrange family remained loyal to Voldemort, with Rabastan Lestrange, brother Rodolphus Lestrange and sister-in-law to the former/wife to the later Bellatrix Lestrange going to Azkaban instead of publicly forsaking him. Voldemort greatly appreciated their loyalty and promised to honour them beyond the dreams of wizards. The Mulciber family served him faithfully with both the Snr and the Jr Mulciber fighting for him and the younger even going to Azkaban for him. The Rosier family served him faithfully, with Rosier being among his first Death Eaters and Evan Rosier dying for him during the First War.
Other individuals who served him faithfully were Antonin Dolohov, Augustus Rookwood, Travers and Wilkes. The first three went to Azkaban for him while the last was killed by Aurors during the First War.
Both Regulus Black II and Severus Snape defected after becoming disillusioned with the Death Eater lifestyle. The later also defected to protect Lily Evans whose husband James Potter I and son Harry Potter were targeted by Lord Voldemort for death, whereas the former defected for the wellfare of Kreacher.
Gibbon, Jugson, Selwyn, and Thorfinn Rowle were also amongst those who served Lord Voldemort. Whether they forsake him or not is unknown.
Jugson and Selwyn, were also Death Eaters but due to many factors, it is hard to determine whether they originally served Voldemort out of loyalty, by being deceived or blackmailed.
Although Fenrir Greyback is not a true Death Eater, Voldemort offered him the privilege to wear their robes in exchange for his services. While Voldemort saw Greyback as a valuable asset in threatening to set him loose onto people who refuses to cooperate, he did not hold the werewolf in the same regard as genuine Death Eaters, and did not brand him with the Dark Mark. Fenrir joined up with Voldemort not for ideologies, but for greater access to victims of werewolfry infection, and did not attempt to find Voldemort after his first downfall. Regardless, the werewolf did resent the fact that he was not being treated with the same level of respect as Voldemort's inner circle (such as not having the Mark), many whom regarded him with disgust and neglect. Indeed, while it is clear that Voldemort only treats all of his subordinates as tools for his bidding, his low respect for Fenrir made it even more apparent.
The Order of the Phoenix
The Order of the Phoenix was a secret organisation founded and led by Albus Dumbledore to oppose Voldemort and his Death Eaters.
Though it was unknown to Voldemort till shortly before his defeat, Severus Snape was a member of the Order who had defected from the Death Eaters and worked for Dumbledore as a spy shortly after Voldemort began hunting Lily Potter.
James and Lily Potter were members of the Order who became prime targets for Voldemort during the First Wizarding War, after Voldemort heard of a prophecy foretelling of a child destined to destroy him. This fit the description of their young son, Harry. On 31 October, 1981, Voldemort found the Potters after the Fidelius Charm they had cast was broken by Peter Pettigrew. Voldemort killed James first and ordered Lily to stand aside, so he could kill Harry. When Lily refused to stand aside, Voldemort killed her as well, making her murder a sacrifice that caused the Killing Curse Voldemort aimed at Harry to backfire; Voldemort lost his body and fled to Albania.
Shortly after Voldemort lost his powers in 1981, the Longbottom family suffered at the hands of Bellatrix Lestrange, her husband Rodolphus, her brother-in-law Rabastan, and Bartemius Crouch Junior, who tortured Alice and Frank Longbottom, new parents to Neville Longbottom, to the point of insanity. They became permanent residents of St Mungo's Hospital for Magical Maladies and Injuries, and Neville was left to be raised by his grandmother, Augusta Longbottom. During the Battle of Hogwarts in 1998, Neville openly defied Voldemort and was tortured. However, he survived, and destroyed Voldemort’s last remaining Horcrux when he beheaded Nagini using the Sword of Gryffindor.
Alastor "Mad-Eye" Moody was a highly skilled Auror and active member of the Order who fought against Voldemort during the First Wizarding War. After Voldemort’s first downfall in 1981, Moody was responsible for rounding up a number of Death Eaters, such as Igor Karkaroff, and killing several others, like Evan Rosier. In 1994, Voldemort ordered Bartemius Crouch Junior to kidnap Moody and imprison him in his own trunk. For the next nine months, Crouch used Moody's hair to brew the Polyjuice Potion that would allow him to take Moody's place as temporary professor of Defence Against the Dark Arts at Hogwarts. In 1995, Crouch used his position at Hogwarts to make sure Harry Potter was transported to the Little Hangleton graveyard, where Peter Pettigrew used Harry's blood in a potion that allowed Voldemort to be restored to his body. When Voldemort failed to kill Harry in the graveyard and Harry returned to Hogwarts, Barty Crouch Jr attempted to murder him personally. Dumbledore, Minerva McGonagall, and Severus Snape rescued Harry, after which Crouch was exposed, and Moody was freed. After Dumbledore’s death in 1997, Moody took charge of the Order of the Phoenix, until he was murdered by Voldemort during the Battle of the Seven Potters.
Nearly all of the Weasley family was active within the Order of the Phoenix. They fought against Voldemort during both the First and Second Wizarding wars. They lost family members such as Fabian and Gideon Prewett, who were brothers of Molly Weasley, and Fred Weasley, who was killed in the Battle of Hogwarts. Voldemort had previously tried to manipulate Ginny Weasley in 1992, in an attempt to return to physical form, through one of his Horcruxes. Voldemort was furious when Molly defeated Bellatrix, and would have killed her, had Harry not intervened. Most of the Weasley family watched the final duel between Voldemort and Harry, and were witnesses to Voldemort’s death.
Dorcas Meadowes, Caradoc Dearborn, the Bones family, the McKinnon family, Benjy Fenwick and Emmeline Vance were all Order members killed either by Voldemort or by his Death Eaters during the First and Second Wizarding Wars.