Director: Lucio Fulci
Technically, Lucio Fulci's The House by the Cemetery is more of a haunted house film than a zombie picture. When the spirit marauding around a house is a long-deceased mad doctor who thrives off of human flesh and blood to keep his grotesque physical appearance intact, though, you're definitely in a walking dead movie.
Besides, the best hauntings require a bit of restraint and subtlety, two words that most certainly weren't in Mr. Fulci's vocabulary. Even though there's only one actual zombie in The House by the Cemetery, the film is sadistic, and, of course, revolting, enough to get by on its scant undead presence.