I don’t think it’s always the actors in name, it’s sometimes what they’re known for.

Look at the recent adaptation of The Odyssey. It’s easy to remember that the name of the main character is Odysseus, it’s basically the title. But his wife? I’m sure it’s said a few times in the film but I don’t remember it, it’s Anne Hathaway. But they also have a son… Uh… Spider-Man.