Right? I'm pretty sure it's the first film of his I ever saw, and nothing I've seen since gives a clue that he had that performance in him.

I saw him in other films first—dramatic parts, even—and none of them gave a clue! I had no idea anything like Danny was hanging out in 1937 Hollywood. He is a truly uncanny object. He made me think of Herbert Farjeon's assertion that supernatural horror is fundamentally reassuring, because the alternative that such people exist who aren't werewolves or vampires is barely to be borne.