King Bill

King Bills are a brand new sub-species of Bullet Bill, which only appears in the last stage from New Super Mario Bros. Wii, World 9-8. It's very large in size, being bigger than even the Banzai Bills. It is the biggest enemy of the game, though it's not bigger than Bowser's giant form after Kamek's spell in Bowser's Castle. King Bills are also invincible, they can only be defeated by jumping in the flagpole at the end of the stage.