Bugs Bunny went out trick or treating as a witch until he came across Witch Hazel's haunted house. The two of them spend many-a antic together. On the side, other Looney Tunes characters ran into Halloween-typed situations themselves (including Daffy & his nephew and their own encounters with Witch Hazel.) In the end, Hazel tried to catch Bugs, but failed when Bugs turned her into another rabbit and instantly fell in love with each other.
A-Haunting We Will Go (1966) (part one) (Daffy Duck's nephew encounters Witch Hazel while trick or treating. Daffy does not believe his nephew and starts heading to the witch's house to prove him wrong).
Broom-Stick Bunny (1956) (Bugs, also trick or treating in the same costume as Daffy's nephew, arrives at Witch Hazel's house. The witch invites him for tea, but when Bugs reveals himself, he begins to leave. Witch Hazel asks him to stay and have the tea, but Bugs instead brags about his doctor's tea, and leaves to prove to the witch that it has "more pizzazz".)
Hyde and Hare (1955) (It turns out that the doctor Bugs spoke of is none other than Dr. Jekyll, and Bugs inevitably comes face to face with Mr. Hyde)
Hyde and Go Tweet (1960) (While Bugs encounters Dr. Jekyll, Sylvester has a dream about his encounter with Tweety)
Hyde and Hare (part two) (Bugs comes across Dr. Jekyll's Hyde formula, believing it to be the doctor's tea. After wondering whether or not it really does have pizzazz, he drinks some of it ("Neh, why not? It's Halloween.") and returns to Witch Hazel as a monster. The witch mistakes Bugs's new form for another costume, and turns him back to normal, causing Bugs to faint.)
A Witch's Tangled Hare (1959) (After attempting to add Bugs to her stew, Witch Hazel chases him all the way to an ancient castle)
A Haunting We Will Go (part two) (Witch Hazel makes Speedy Gonzales into her exact double so that she can take a much needed vacation. She dips cheese in her witch's brew after he asked to borrow a cup of cheese. He (Gonzales) isn't good at acting like a witch. He stands in for the witch while Daffy tries to prove his nephew wrong about her. Speedy makes tea that turns Daffy into the strange creature from Duck Amuck. The witch returns and disgusted with Speedy's "botched up job" turns Speedy and Daffy back to normal, then starts eyeing Daffy menacingly for a possible duck dinner.)
Claws for Alarm (1954) and Scaredy Cat (1948) (Bugs meets up with Witch Hazel again at a hotel, telling her that he is unimpressed with her spells. The witch decides to put a spell on Sylvester, who has to spend the night in the hotel with Porky Pig while enduring murderous mice. Eventually, Sylvester can not take it anymore and runs away from the hotel.)
Transylvania 6-5000 (1963) (Bugs, impressed with Witch Hazel, gives her the Hyde formula (which he has grown disgusted of) and leaves the hotel. Upon drinking the formula, the witch transforms into a vampire and proceeds to stalk Bugs while he explores her place.)
Bewitched Bunny (1954) (Bugs unwittingly restores Witch Hazel back to her natural form, and she declares, "Okay, rabbit, you've spelled your last spell. Now it's my turn!" She chases Bugs into a hallway with no escape, but Bugs finds her emergency supply of magic powder and transforms the witch into a female bunny, whom Bugs sees as a love interest ("Sure, I know, but after all, who wants to be alone on Halloween?"). In an epilogue, the two rabbits celebrate Halloween by drinking the stew from Witch Hazel's cauldron, but Bugs comments that it needs salt.)
The special was released on VHS in 1994, and reissued on DVD in 2010.