Quackerjack is a toymaker who has gone insane and who wears a harlequin-style jester costume. Quackerjack uses his arsenal of dangerous toys as weaponry while he commits crimes or just causes chaos for the fun of it. He is almost never without his trademark doll, Mr. Banana Brain. His most common toys are mechanical toy chattering teeth of various sizes. He has been known to team up with Megavolt occasionally. He also appears in the Dakwing Duck comics. In the comics by Boom! Studios, Quackerjack becomes a more dangerous villain; hurting from Negaduck destroying Mr. Banana Brain and telling him he is not "mean enough" to be a serious villain, then becoming bitter and angry when he fails to fit in at Quackwerks, and viewing others' success as a "rejection of him", he becomes determined to show "the world he is mean enough", but after a series of more evil crimes, he grows tired of being more evil and turns himself into a toy outside his old girlfriend's house, believing "this is the best I can ever be". He is later brought back by Negaduck's "slime". His name is a pun on the word "crackerjack". He is an obvious spoof of Batman's nemesis, the Joker.