You don't see much in the genre of comedy-horror these days. Comic thrillers from people like the Coens, Johnathan Demme, Sam Raimi, and more, sure - but a movie with true horror tinged with comedy is a rare thing. To clarify further, I'm not talking about horror spoofs like Scary Movie, either. Even though his movies might not be scary in that viscerally terrifying way that some people need in order to call a movie "scary," I'd like to nominate Roger Corman as a master of comedy/horror, in part because of his work on perhaps the peak example of the form: A Bucket of Blood.
The movie is a bit of a two-headed monster: It's a story about a lonely Norman Bates-type character who murders people and then uses their bodies to make sculptures. It's also a fascinating and hilarious satire of late-50s Bohemia, poking fun at the world of pompous "artistes" and the people who profit from them.
One of the reasons I love this movie is because, to me, there's no more impressive feat in mainstream film than making a movie funny and also tense/scary/creepy/suspenseful at the same time. And while this movie isn't exactly The Texas Chainsaw Massacre when it comes to scares, it is pretty creepy. Plus, even though it's a comedy, it doesn't pull any punches - Dick Miller's character Walter, lovable as he is, is really killing people. And at the end of the movie, he chases after his "love interest" to try to make her into a sculpture after she admits that she doesn't love him. Miller's great, by the way. Kind of a kooky riff on Norman Bates, albeit a year before Psycho came out (wonder if Hitchcock saw this?).
Anyway, this is absolutely one of Corman's best movies (of particular interest might be how Corman integrates the title of the movie into the story), in addition to being one of his funniest. Check it out, if so inclined.