The Joker is a fictional person.
Joker (character) . In his comic book appearances , the Joker is portrayed as a criminal mastermind . The antithesis of Batman in personality and appearance , the Joker is considered by critics to be his perfect adversary . One of the most iconic characters in popular culture , the Joker has been listed among the greatest comic book villains and fictional characters ever created . The Joker has been adapted to serve as Batman 's adversary in live-action , animated , and video game incarnations , including the 1960s Batman television series ( played by Cesar Romero ) and in film by Jack Nicholson in Batman ( 1989 ) , Heath Ledger in The Dark Knight ( 2008 ) , and Jared Leto in Suicide Squad ( 2016 ) . The Joker is a fictional supervillain from American comic book publisher DC Comics and the main antagonist in Christopher Nolan 's 2008 superhero film The Dark Knight .