Jack Nicholson's Joker, as seen in 1989's Batman, is one of the best-remembered versions of the character, and he's certainly great fun to watch. But he's scarcely nastier than his original identity of Jack Napier, the gangster who (in the movie version) killed Bruce Wayne's parents. Before the chemical accident that ruined his face, Napier was already homicidal and venal and already a little unhinged, asking his victims a meaningless riddle before shooting them dead. In other words, changing him into the Joker didn't really seem to make that much difference, which ultimately diminished the story. What Fixed It: The Killing Joke, which came out a year earlier, showed a much more dramatic transformation and was a lot more influential. Many versions of the character (such as the one in Christopher Nolan's The Dark Knight (2010)) also give him no definite origin story at all.