Negaduck is the evil Darkwing from another dimension, known as the Negaverse. There he conquered Saint Canard, and presumably the entire world. Since his only opposition had been the friendly four (heroic, but cowardly versions of Megavolt, Liquidator, Bushroot, and Quackerjack.) He figured he would head to another dimension, and have a repeat performance. However once he got there, he soon got into conflict with Darkwing Duck. The two would clash many times, with schemes ranging from impersonating Darkwing, to pretending to reform, so he could get close to him. He would also steal the powers of the rest of the fearsome five for a short time. In the comics, he would spot Launchpad at the local dry cleaners. Seeing the Darkwing Duck costume, Negaduck would discover Darkwing Duck's secret identity, and ambush their home with a tank. The Quackerwerks crime bots would stop him however. This would result in Drake Mallard retiring from Darkwing Duck for a few years. Negaduck would later team up with the Ducktales villain, Magica Despell, to summon hundreds of alternate Darkwing's to ruin the original's reputation. When this failed, he made a deal with the evil spirit Paddywhack, and gained shadowy powers. However Darkwing would manage to defeat him once again. This time he was broken down into millions of atom's, spread all over the cosmos. However no one as evil as Negaduck stays down for long.....
Mega-Negaduck
Negaduck and Magica