Charisma is something that can’t be learned in acting school. Actors either have it, or they don’t.
Please see Steve McQueen
Another one. When McQueen first appeared on the scene to many Americans it was in his western “Wanted Dead Or Alive.” People just liked McQueen. He certainly was no great actor (or ham) and not conventionally handsome, but people wanted to see more of him. He had that appeal that all the pretty boys of the fifties like Tab Hunter, Troy Donahue, and others like them lacked. None of those guys had what it took to get the male audience.