Night of the Creeps
Sci-fi/horror/comedy about a college town that's overrun by slug-like alien beings that enter people's bodies through their mouths and then multiply inside their brains, turning them into zombies until their heads eventually burst.
Most people would probably dismiss this as just a generic sci-fi/horror B movie, but I think it works very effectively as a tongue-in-cheek homage and spoof of classic sci-fi films. Despite its humorous tone though, it still has some genuinely creepy moments IMO.
However, I think its biggest selling point is actress Jill Whitlow, one of the hottest babes of the '80s IMO. (Here she is in an unrelated TV role:
Incidentally, there are two endings to this movie (the original theatrical one and an alternate "director's cut"), both of which I've seen in TV airings. The director's cut is admittedly more chilling and creative, but I prefer the original within the context of the movie.