where did the concept of this character emerge from?
Bill Finger, Bob Kane, and Jerry Robinson are credited with creating the character. The concept started with Finger produced an image of actor "Conrad Veidt" in character as “Gwynplaine" in the film "The Man Who Laughs" as an inspiration for the Joker's appearance, and Robinson produced a sketch of a joker playing card.
Joker (character)
Bill Finger, Bob Kane, and Jerry Robinson are credited with creating the Joker, but their accounts of the character's conception differ, each providing his own version of events. Finger's, Kane's, and Robinson's versions acknowledge that Finger produced an image of actor Conrad Veidt in character as Gwynplaine (a man with a disfigured face, giving him a perpetual grin) in the 1928 film "The Man Who Laughs" as an inspiration for the Joker's appearance, and Robinson produced a sketch of a joker playing card.
who was the joker before he went crazy A story about the Joker's origin appeared in "Detective Comics", here, the character is a laboratory worker who becomes the Red Hood to steal 1 million dollars and retire.
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Joker (character) [SEP] Concept
Bill Finger, Bob Kane, and Jerry Robinson are credited with creating the Joker, but their accounts of the character's conception differ, each providing his own version of events. Finger's, Kane's, and Robinson's versions acknowledge that Finger produced an image of actor Conrad Veidt in character as Gwynplaine (a man with a disfigured face, giving him a perpetual grin) in the 1928 film "The Man Who Laughs" as an inspiration for the Joker's appearance, and Robinson produced a sketch of a joker playing card. Robinson claimed that it was his 1940 card sketch that served as the character's concept, and that Finger associated with Veidt's portrayal.