The Joker served as Batman 's adversary in Cameron Monaghan 's Proto-Jokers in Gotham ( TV series ) .
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 films : by Jack Nicholson in Batman ( 1989 ) ; Heath Ledger in The Dark Knight ( 2008 ) ; Jared Leto in Suicide Squad ( 2016 ) ; and Joaquin Phoenix in Joker ( 2019 ) .
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