The Real Joker
Not many people know that the famous character of the Joker was inspired by a German actor named Conrad Veidt. He always took on very eccentric roles that were never before seen in his time, and his most famous role was as Gwynplaine in The Man Who Laughs.
Gwynplaine is a scary, deformed man with a hideous smile that goes through his cheeks (just like the Joker), which he got as a punishment for offending the King of England. He was punished by getting a "permanent smile" done by a surgeon and can never stop smiling. Sounds familiar, right?