City of Villains is a massively multiplayer online role-playing computer game based on the superhero comic book genre, developed by Cryptic Studios and published by NCSoft. Released on 2005-10-31 (Halloween), the game is integrated with their previous release, City of Heroes. The gameplay centers on defeating a variety of computer controlled opponents within a three-dimensional world using various powers and attacks, sometimes with the help of several other players.

As City of Villains is an expansion to City of Heroes as well as its own standalone title, it features several changes that are unique to its players, unless they also have a copy of the original game. One of the primary changes to the game was the ability to play as a supervillain, with new Archetypes (classes) and powers unique to Villains. Other changes to the game include:

An instant-access mission system.

Player vs Player areas for hero vs. villain conflict.

Build your own Super-Villain lair.

Sharper and more detailed graphics, ragdoll physics, and other visual improvements.