Asked in Celebrity Relationships It's understandable that one might think they're related; they're of the right age to be brother and sister. Because the two stars share the same last name, many fans have wondered if Diane, 71, and Michael… Michael Keaton was born with the last name Douglas, and Diane's real last name is Hall. Michael Keaton and Diane Keaton are not related through family ties. Michael and Diane Keaton are not actually related, and oddly enough neither of them was born a Keaton. Wait, are Michael Keaton and Diane Keaton related?