Negaduck is often being dubbed Darkwing's "evil twin". Not much is known about Negaduck's place of origin, but a clue is that he rules the Negaverse (a possible antimatter universe analogue), a parallel universe similar to the original St. Canard (home to Darkwing Duck), but Evil reigns supreme there. He has even revealed that the Negaverse is his "secret hideout", which can only be accessed via a portal within the hollow shell of a papier-mâché cake inside a local bakery in the original St. Canard.
Negaduck's arsenal is filled with many destructive weapons that are known to cause major harm, i.e. chainsaws, flamethrowers, and even a nuclear missile.
Negaduck has been known to lead a band of villains he has dubbed the Fearsome Five, which also consists of Megavolt, Reginald Bushroot, Liquidator, and Quackerjack. He always takes advantage of the belief that he is the smartest of the group and has tried to prove it often.
Negaduck has also taken advantage of the fact that he greatly resembles Darkwing Duck, and has tried to frame his good counterpart for committing crimes while disguised as the famed hero. However, this has gotten him in trouble once, because he'd instigated the public to put a price on Darkwing Duck's head, and he'd been mistaken by a mob for Darkwing Duck in a color-change disguise (which, ironically, is his own trademark costume).
Negaduck is violently upset that he is not Public Enemy #1, as he has taken second only to a villain named Dr. Slug for many years. Because of this, he usually tries to think up a diabolical plan that will earn him that title.