Moon Knight
In his first appearance in 1975, Marc Spector was hired as a mercenary against the protagonist of the comic book Werewolf by Night, Jack Russel.  Editors Len Wein and Marv Wolfman then decided that instead of being an antagonist, Moon Knight would be a superhero. Moench and Perlin then wrote a story giving him a secret identity as a millionaire named Steven Grant. Moench then decided to write a story where Steven Grant uses the alias Jake Lockley. As Lockley, he pretends to be a taxi driver to find information about criminals. This was done so that Marc Spector would have more than one secret identity.  Moench wrote two comic books where Marc Spector joked that he had schizophrenia. He wrote another where his girlfriend asks Marc if he has a split personality and he says he knows he is just acting when saying he is Steven Grant or Jake Lockley.   After Moench left the comic, writer Steven Grant wrote the story so that Marc Spector had multiple personality disorder.