The Negaverse is a parallel universe of St. Canard, that appears in the Darkwing Duck episode "Life, the Negaverse, and Everything", and is the home of the villainous Negaduck. Everything in this universe is the opposite of the regular universe: crime rules the streets, villains are the good guys, and Negaduck rules supreme.
The entrance to the Negaverse is a portal inside a big birthday cake, hidden in a "Sugar, Spice, and Everything Nice" bakery.
Using the birthday cake portal, Negaduck is able to visit the regular universe and return to his own universe whenever he wishes to. He keeps the portal a secret from his criminal colleagues until they follow him to his secret hideout. When Darkwing Duck shows up, Megavolt, Bushroot, Quackerjack, and Liquidator capture him and throw him into the portal, with no idea of where it leads to. Furious of what they just did, Negaduck goes after Darkwing.
When Darkwing Duck arrives in the Negaverse, he finds the city to be a dark and dimmed world flooding with noxious fumes, crippled buildings, dead plant life, and the streets roaming with crime.
Darkwing comes across parallel versions of Gosalyn and Launchpad and with the help of the Negaverse Tank, he explains what had happened. At first, Darkwing refuses to believe that he is in another universe, but after trying to wake himself up by bashing his head against a wall (thinking it is all a dream), he finally believes that he is in the Negaverse. He is about to leave, when he is asked to stay by the Friendly Four (parallel versions of Megavolt, Bushroot, Quackerjack and Liquidator), to help them defeat Negaduck.
With Darkwing's help, the Friendly Four are able to restore the city to the beauty of the regular universe St. Canard. Darkwing Duck leaves the Negaverse, with Nega-Gosalyn in the care of the Friendly Four.
- The name Negaverse is a combination of the words "Negative Universe", much like Negaduck's name is a combination of the words "Negative Darkwing Duck".
- The Negaverse is an example of a classical "mirror universe" where all the heroes are villains and all the villains are heroes. Non-Disney examples of this are Earth-Three and the Anti-Matter Universe in DC Comics, the Shattered Glass Universe in Transformers, Anti-Mobius in the Sonic the Hedgehog comics, and of course, the Mirror Universe from Star Trek.
- The name "Negaverse" is even used in the English dub of Sailor Moon as the translated name for the Dark Kingdom of the original Japanese anime.
- NegaGosalyn, while opposite of Gosalyn personality wise, is one of the few counterparts who are still on the same side morally as their main universe counterpart.
- The Muddlefoot family is different in a subtle way as well. Unlike the normal versions, Herb and Binkie actually listen to Honker (who has the most common sense in their family).
- Aaron Sparrow had planned to do a story returning to the Negaverse, including an appearance by its version of Gizmoduck, for Joe Books' Darkwing Duck revival comic, but due to Disney cancelling the comic, that story is unlikely to ever be published.