Most famous silent actor to be the most famous talky actor

Ronald Colman was a sex symbol in silent films, and his rather unique voice and phrasing kept him in that spot in the talkies, well into the forties, when he seamlessly transitioned into middle-aged father figures. He could play anything from a wastrel drunken lawyer (Tale of Two Cities) to a very upright supreme court justice (Talk of the Town) and could hold his own with Cary Grant and Douglas Fairbanks Jr. in getting the girl. He is largely forgotten today, and I think virtually unknown to anyone under 50, which is too bad.