The dad from Gremlins (can't you just follow instructions, dude; look what hell you hath wrought)
Bruce the shark from Finding Nemo (I know he winds up as a good guy and is trying to amend his evil ways, but still)
Saruman
Jabba the Hutt (but he has great taste in slave girl attire)
Montgomery C. Burns (yes, I know he's TV based)
The Joker
Lex Luthor (played to perfection by Gene Hackman)
La Fours (see who can get that one)
Azrael (Jason Lee in Dogma; c'mon, his death by blessed seven iron was almost as cool as dying by lightsaber)
Curly Bill Brocious and Johnny Ringo
The gremlin from Twilight Zone's "Nightmare at 20,000 Feet" (both versions)