Which Marvel Comics character with severe mental illnesses appear in the pilot episode of the American cable television series named after the character?
Chapter 1 (Legion): "Chapter 1" is the pilot episode of the American cable television series "Legion", based on the Marvel Comics character David Haller. Legion (Marvel Comics): Legion (David Charles Haller) is a fictional superhero appearing in American comic books published by Marvel Comics. Legion (Marvel Comics):  Legion takes the role of an antihero who has a severe mental illness including a form of dissociative identity disorder, in which each of his alternate personas controls one of his many superpowers.
Legion