Revan is a fictional character in the BioWare video game Star Wars: Knights of the Old Republic, in which he is the playable protagonist. He also appears in related media in the Star Wars expanded universe.
The character is a former Sith suffering from amnesia, having been brainwashed with a false identity by the Jedi to serve their cause. This is only made known to the player late in the game, prior to which the playable protagonist lacks any predefined identity and Darth Revan is believed to be dead.
Revan (who is, per above, not identified as such during the character creation process) is customized by the player in terms of appearance, gender, and actions; canonically, Revan is male and follows the light-side path during the events of the game.
Revan’s story is further explored in Drew Karpyshyn‘s 2011 novella Star Wars: The Old Republic: Revan. The book details the events of Revan’s life after the events of Star Wars: Knights of the Old Republic, in which Revan attempts to recover his lost memories from the period of the Mandalorian Wars and from his and Malak’s travels to discover the Sith empire. In the massively multiplayer online game Star Wars: The Old Republic, an incarnation of Revan serves as the titular antagonist of the Shadow of Revan expansion.