Paddywhack is the main antagonist in the episode "The Haunting of Mr. Banana Brain" of Disney's Darkwing Duck. He is an ancient evil duck spirit from another dimension and an obvious homage to Pennywise of Stephen King's It. He may be the darkest entity in the duck universe since he feeds off negative emotions, pranks, and general mischief. His appearance makes the show grimmer, despite the writers' attempts to keep it humorous.
Paddywhack often mentions how much he likes and desires to eat, and the several times that he is seen drooling certainly makes it seem like he feeds on people (and at one point, Launchpad certainly comes to mistakenly believe that he is carnivorous due to him drooling at the sight of him, Darkwing, and Gosalyn). But while he is certainly not against devouring hapless people who cross his path, as previously mentioned, his main diet consists of negative emotions like pain, misery, and sorrow, and other emotions caused by pranks played on people.
He was voiced by the late Phil Hartman in Darkwing Duck, and Jim Cummings in the DuckTales reboot.
Paddywhack was trapped inside a jack-in-the-box, but woke up after Gosalyn played a prank on her father using a joy buzzer while they were visiting a toy museum. When Quackerjack burst onto the scene and started playing pranks on everyone, Paddywhack got stronger and was freed from the box. As the episode title implies, he possessed Quackerjack's doll, Mr. Banana Brain, providing a macabre laugh when the mentally unstable toymaker only noticed a change in the usually-lifeless doll's voice.
Since Quackerjack was already insane, yet easy to lead and childish in nature, he was perfectly suited to be the demon's puppet. That is, until he decided to trap him and Darkwing (who sent himself there to protect Gosalyn from going there herself) in his jack-in-the-box, send them to his twisted dimension, and inflict on them an endless supply of suffering for all eternity. He started out by forcing Quackerjack (and Mr. Banana Brain, as well!) to wear a businessman's suit (which went against his fun-loving nature) and Darkwing to wear an endless supply of clown costumes (to go against his more serious nature). The two, however, teamed up and started goofing around, which severely weakened the demon due to the joy they were projecting rather than misery, forcing him to expel the two from the box.
Darkwing, Launchpad, and Gosalyn then disposed of the box, throwing it into the river, and the box ended up being swallowed by a fish. The end of the episode implied that Paddywhack somehow escaped the box, however, and possessed the fish, much to the heroes' shock and horror.