I know this is a tricky question because most villains will end up being seen as scary and terrifying, even if your initial impression of them was as harmless or just different. Jason Voorhees, Ghostface, or Freddy Krueger, of course, are villains that look scary from the get-go.

Christoph Waltz, nevertheless, is not someone I would call scary-looking. Not at first. Yet, by the end of the first major scene in the movie Inglourious Basterds, in which you are introduced to him as Standartenführer Hans Landa and get to see glimpses of what he is capable of, you are already seeing him as at least a little terrifying. And this gets reinforced in several other key scenes in the movie.

That really speaks to Waltz's talent and great writing. Though I did not overall really care for the movie overall, at least certain parts of it, I think Waltz deserved the Oscar and did a fantastic job.

Can you think of other examples of non-scary looking evil characters?