Clowns - supposed to be funny, but more often than not, creepy. The make-up, meant to emphasize their own features, becomes exaggerated, a parody of a person. And although small children recognise and relate to large facial features - the big eyes especially - I'm sure many of them get overwhelmed and frightened by the clown creatures. I don't like clowns myself, and I don't know how that happened. Their antics are funny enough. But that make-up...

The fear of clowns is called coulraphobia. :)