Cowboy Bebop/Nightmare Fuel

Pierrot le Fou. Basically, a balloon-esque, practically invincible manchild with a permanent Slasher Smile spends the entire episode floating around, laughing, trying to kill the protagonist. His defeat is even better. He gets trampled to death by a parade of creepy, animatronic amusement park mascots the size of small buildings, all while screaming like a child in the grips of a nightmare from which there is no escaping.