This is a list of playable and boss characters from the Mortal Kombat fighting game franchise and the games in which they appear. Created by Ed Boon and John Tobias, the series depicts conflicts between various realms. Most characters fight on behalf of their realm, with the primary heroes defending Earthrealm against conquering villains from Outworld and the Netherrealm. Early installments feature the characters participating in the eponymous Mortal Kombat tournament to decide their realm's fate. In later installments, Earthrealm is often invaded by force.

A total of 77 playable fighters have been featured in the series, in addition to unplayable bosses and guest characters. Much of the franchise's mainstays were introduced during the first three games. Nearly all of the characters have been killed at a point in the story, but have rarely stayed dead.