Whatever function Renfield may or may not serve in the 1931 Dracula I cannot image the movie without him. Renfield's worth it for Dwight Frye's extraordinary over the top performance. While I wouldn't say he steals the picture from Bela Lugosi (not Lugosi, not in this film), Frye makes the movie shake, rattle and roll whenever he's on screen, or rather after his early scenes (he's good in those, too, but he's just warming up). From his first "mad scene" he's superb.