The Dursley family is a Muggle family, and the only known living close relatives of Harry Potter. Petunia Dursley (née Evans) was the older sister of Harry's mother, Lily Potter (née Evans), but took the surname Dursley when she married Vernon Dursley. They had a son named Dudley.
Harry Potter's aunt and uncle met at work. Petunia Evans, forever embittered by the fact that her parents seemed to value her witch sister more than they valued her, left Cokeworth forever to pursue a typing course in London. This led to an office job, where she met the extremely unmagical, opinionated, and materialistic Vernon Dursley. Large and neckless, this junior executive seemed a model of manliness to young Petunia. He not only returned her romantic interest, but was deliciously normal. He had a perfectly correct car, and wanted to do completely ordinary things, and by the time he had taken her on a series of dull dates, during which he talked mainly about himself and his predictable ideas on the world. During one particular date when they were sitting in his car in front of a chip shop she tearfully confessed about her strange sister. As she had expected, Vernon was quite shocked, though he comforted her and told her it wasn't her fault for having a "freak" for a sister and that he would not hold it against her. He finally proposed to her in his mother's (very ordinary) living room, it was all very emotional.
Due to Petunia's maternal connection to Harry Potter, Harry was sent to live with the Dursleys after his parents were murdered by Lord Voldemort. The belief was that Lily's maternal sacrifice for Harry would be transmitted through Petunia, even though she held Harry in contempt. Due to his wizarding background, Harry was treated with fear and negligence by the Dursleys; originally being kept oblivious to his wizarding heritage, and being told that his parents had died in a car accident.
The Dursleys lived at 4 Privet Drive in Little Whinging, Surrey, and often went out of their way to keep their neighbours oblivious to anything odd about their family, usually explaining away anything odd by telling people that Harry was a delinquent who went to a detention school far away. Harry did occasionally update them about Voldemort and the Death Eaters. Because of their family connection to Harry and the danger of Voldemort using them to get to Harry, they were forced to go in hiding for their own safety for a period of time during the height of the Second Wizarding War.
Despite his mistreatment of Harry, Harry's cousin Dudley Dursley eventually came to regret his cruelty towards Harry, and the two reconciled later in life; this was mostly due to an incident in the summer before Harry's fifth year of schooling that involved him saving Dudley from a Dementor.
Vernon Dursley is Harry's abusive uncle, Petunia's husband (and therefore Lily Potter's brother-in-law), Dudley's father and Marge's brother. Vernon is described as a big, beefy man, the literal human embodiment of a walrus, with hardly any neck, and a large moustache. He is very much the head of his family, laying down most of the rules for Harry and doing most of the threatening, as well as spoiling Dudley. He is also the director of a drill-making firm, Grunnings, and seems to be quite successful in his career. He regularly reads the Daily Mail.
Uncle Vernon and his wife have grudgingly raised Harry from an early age. He and Petunia were often hostile to Harry and never informed him about the magical world, including how his parents died; they explained it away as a car crash. Unlike Petunia, who proves to have a slight feeling of familial loyalty to Harry, Vernon seems to hate his nephew so much that in Harry Potter and the Order of the Phoenix, he is willing to throw him out of the house, knowing that doing so would put him in grave danger. In fact, while discussing the Dementor attack with Harry, Vernon actually hopes aloud that Harry will receive the death penalty. Vernon also has an aversion to imagination, to any references to magic, and anything even slightly out of the ordinary; in the first book, when Harry mentions dreaming about a flying motorbike, Vernon responds by angrily bellowing that motorbikes do not fly, despite Harry's protests that it was only a dream.
When the Dursleys decide to leave Privet Drive to go into hiding, Vernon nearly shakes Harry's hand good-bye, though he ultimately cannot bring himself to do it. In the film version, he leaves without even a word to Harry although a deleted scene showing Dudley and Harry's reconciliation shows him saying "this is farewell".
Vernon is portrayed by Richard Griffiths in the film series.
Petunia Dursley is Harry's maternal aunt, Lily Potter's older sister, Vernon's wife, Dudley's mother and Marge's sister-in-law. She is described as a bony woman with blonde hair that she passed down to her son, a "rather horsey" face and a very long neck, and spends most of her time spying on her neighbours. Her eyes are large and pale, quite unlike Lily's. Her whole family prior to Lily are made up of Muggles. According to Petunia, her parents were proud of having a witch in the family, but Petunia saw her sister as a freak. In fact, she was envious and resentful of Lily's magical abilities and went so far as to write to Dumbledore, pleading to be allowed to enter Hogwarts. Dumbledore gently denied her enrollment. Afterwards, Petunia grew bitter towards the school and, by extension, towards the wizarding world in general. She had no contact with Lily after her marriage to James Potter and the birth of her nephew, Harry, though she did send the family a "horrible vase" that baby Harry broke while riding on a toy broom. The gift echoes Harry's Dursley-sent Christmas presents, which are never pretty or welcome.
Petunia has more knowledge of the wizarding world than she is initially willing to admit. After the Dementors attack Harry and Dudley, Petunia states that she knows Dementors guard the wizard prison, Azkaban. When Harry and the rest of her family look at her strangely, she explains that she heard "that awful boy" telling Lily about them years ago. Harry assumes that the "awful boy" was his father, James, but in Harry Potter and the Deathly Hallows, he learns via flashback memories that it was actually Severus Snape, who knew both Lily and Petunia when they were children. On one occasion, Petunia, but mostly her husband, almost throws Harry out of their house, but when she receives a Howler from Albus Dumbledore, she decides not to send the boy away due to the agreement she had made with Dumbledore (although she covers by claiming that her decision is based on what the neighbors might think if the Dursleys threw Harry out).
Before the Dursleys leave Privet Drive to go into hiding, Petunia almost wishes Harry good luck, suggesting that she does feel a tiny sense of familial attachment to her nephew; however her self-imposed dislike of magic prevents her from doing so, and she leaves without a word. In the film version of Harry Potter and the Deathly Hallows – Part 1, she leaves Harry without showing any sentiment; however, in a deleted scene on the Blu-ray/DVD release, Petunia shows acknowledgment of the wizarding world, and ultimately deep sadness and remorse for the loss of her younger sister Lily, reminding Harry that she lost a sister as well. Petunia Dursley dies sometime between The Battle of Hogwarts and 19 years later.
Actress Fiona Shaw portrays Petunia in the films, with Ariella Paradise playing her as a child.
Dudley Dursley is the only child of Vernon and Petunia, Marge's only nephew and Harry's only cousin. Described as a very large, blond boy (though dark-haired in the films), Dudley is generally given his way in almost everything, and shows the symptoms of a spoiled brat. Dudley is a cold-hearted bully and the leader of a gang of thugs with whom he regularly beats up Harry and younger children on the flimsiest of excuses. He is only one month older than Harry, meaning that his birthday must be sometime in late June. The same year Harry starts at Hogwarts, Dudley is enrolled at his father's old private boarding school, Smeltings.
In Harry Potter and the Philosopher's Stone, Dudley is given a pig's tail by Rubeus Hagrid which has to be removed at a private hospital in London. In Goblet of Fire, the Smeltings school nurse advises the Dursleys to put him on a strict diet. During the summer when this diet is enforced, the Weasleys arrive at Number 4, Privet Drive to pick Harry up for the Quidditch World Cup, and Fred Weasley "accidentally" drops a Ton-Tongue Toffee, which enlarges Dudley's tongue to four feet long before his hysterical mother reluctantly allows Arthur Weasley to shrink it.
In the fifth book, two Dementors attack Dudley and Harry in an alley. Dudley collapses, and Harry uses the Patronus Charm to drive a group of Dementors away from himself and his cousin. Mrs. Figg then comes running in and reveals she is a Squib by talking about Dementors. Harry and Mrs. Figg carry the shaken Dudley home, though Dudley is convinced that Harry made the dementors appear in the first place. After the confrontation, Harry wonders what sort of bad memories Dudley could have relived, as Dementors force people to relive their worst experiences. Rowling later revealed, in an on-line chat, that Dudley's worst fear was seeing himself for who he really was: a cruel, selfish, violent bully with no feelings whatsoever for others, and this revelation shocked him to the core. The experience does give Dudley a more favourable impression of Harry, as seen in Deathly Hallows, when Dudley is the only member of the family to accept Harry: he shakes his hand and thanks him for saving his soul from the Dementor attack, and shows some concern for him when the Dursleys leave to go into hiding. In his appreciation of his cousin's belated gratitude, Harry says good-bye to him using Dudley's former nickname, "Big D". In the film version, however, there is no such sentiment as Dudley leaves Harry before he can say any final words; however, on the Blu-ray/DVD release, a deleted scene includes the reconciliation between the two cousins.
Rowling revealed on her website that many people have asked her to include an adult Dudley with a wizarding child in the epilogue of Deathly Hallows, and that she herself considered it, but decided upon reflection that any "latent wizarding genes would never survive contact with Uncle Vernon's DNA" and thus she did not do so. Rowling says that Harry and Dudley would "stay on Christmas card" terms for the rest of their lives, and that Harry would take his family to visit Dudley's when they were in the neighbourhood, but it was something that James Sirius, Albus Severus and Lily Luna "would dread". However, Dudley's kids and Harry's occasionally would "get together while the adults sat in awkward silence". In Harry Potter and the Cursed Child it is also mentioned that adult Dudley sent Harry his baby blanket, the only surviving possession of Harry's from his parents.
Dudley is portrayed by Harry Melling in the Harry Potter films. Melling had to wear a fat suit, as he lost a considerable amount of weight as the films progressed.
Marjorie Eileen "Marge" Dursley is Vernon's sister and described as physically resembling him; a large woman with hardly any neck and even a bit of a moustache, even though it is not as bushy as Vernon's. Though she is not a blood relative of Harry, he has been forced to call her "Aunt Marge" throughout his whole life with the Dursleys. Marge lives in the country, where she breeds bulldogs and because of her commitment to her animals, she rarely visits Privet Drive, to Harry's considerable relief. She adores her nephew, Dudley and treats Harry with contempt and cruelty. Owing to Vernon's and Petunia's lies, Aunt Marge believes that Harry is a horrible boy, and delights in insulting both him and his dead parents. In Harry Potter and the Prisoner of Azkaban after she insults Harry's parents, Harry loses his temper and accidentally inflates her, thus causing her to blow up like a monstrous balloon and float up to the ceiling. Marge is later rescued, changed back to normal, and the Ministry of Magic modifies her memory. She also appeared in a memory in Harry Potter and the Prisoner of Azkaban: When Harry is chased up a tree by one of Marge's bulldogs named Ripper.
Pam Ferris appeared as Marge in the film adaptation of Harry Potter and the Prisoner of Azkaban, in which she floats out of the house and into the sky after being inflated.