Created by Bill Finger, Bob Kane and Jerry Robinson, the 'Joker' debuted in the first issue of DC Comics' "Batman"...
...inspired by the German Expressionist film "The Man Who Laughs", based on the novel by author Victor Hugo.
In "The Man Who Laughs", actor Conrad Veidt plays 'Gwynplaine', whose face is permanently disfigured into a grotesque grin, after offending 'King James II'.
Gwynplaine becomes a traveling freak, selling his disfigurement for money, while falling in love with a blind woman.
DC's 'Joker', is usually portrayed as a deranged, criminal mastermind, with a warped, sadistic sense of humor.
He evolved into a 'goofy prankster' in the late 1950's in response to regulations by the 'Comics Code Authority'...
...before returning to his darker roots.