the Boy Meets world Halloween episode when they all get locked in the school overnight with a serial killer and Mr. Finny takes a pencil to the skull
also agree with those who mention the Samurai Champloo one and all the South Park ones
my personal favorite South Park Halloween was the woodland critters episode, the scene when Stan first finds out they're Satanic and they sacrifice one and have a blood orgy is maybe the funniest moment in the entire series
i loved the treehouse of horror that was Edgar Allen Poe inspired with Homer as the narrator of The Raven
"Quote the Raven, eat my shorts" lol