--the Town Clown on "Captain Kangaroo". My mom reports me harboring a deep terror of him, but I can't really remember. I DO remember a brief fear of Dancing Bear, though.
--R2D2 and CP-30 from Star Wars. The theme music was scary, too. R2D2 was responsible for a lot of childhood nightmares about robots taking over the earth. Never mind that we never once watched the movie. My dad, sitting up in the middle of the night listening to me tearfully describe my robot nightmares, must've thought I was crazy.
--skeletons.....we had a set of children's encyclopedias and one of them had a full-page photo of this (or one very similar to it):
It was THE most terrifying thing ever (besides the moth section) and I would not even touch the volume that contained the photo.