Batman was originally created to be violent and graphic. In fact, he’s the first anti-hero ever created.
Even the Tim Burton movies were far too campy. It was only until the reboot in 2005 that did the character justice.
He’s not the first anti-hero ever. Maybe the first 20th century anti-hero, definitely the first 4 color anti-hero, but the concept itself dates back to Homer and the word to the early 18th century.