King Bill

King Bills are a sub-species of Bullet Bill that have so far only appeared in the final level of New Super Mario Bros. Wii, World 9-8.

King Bills are invincible, and unable to be beaten with any maneuver or item, and can only be avoided by bouncing above them with clouds or avoiding their deadly paths. Even a Star cannot neutralize a King Bill, but it can keep one from harming Mario.

The player is warned about the incoming King Bills in the form of Coins that make a Bullet Bill shape design and several stone blocks that cannot be destroyed by anything except the Bullet itself. If Mario is standing on these stone blocks as the King Bill bursts through them, he will fall through onto one and lose a life. The player must make sure that they aren't standing on any such blocks during such a violent destruction. King Bills will also destroy any other blocks in the area.

Mario must also avoid going too high to avoid the King Bills. Since the whole level has clouds at the bottom that make Mario bounce very high, he occasionally must try to bounce under the stone blocks to avoid going too high and not hit them. At the end of the level, a King Bill will chase Mario, and he must get under it and reach the end-level flagpole. Like Banzai Bills in Super Mario World, King Bill Blasters are not seen on screen.

They are very large in size, taking up nearly the entire screen, which makes it much larger than the previous biggest Bill, the Banzai Bill. It is the biggest non-boss enemy of the game, being beaten out only by Bowser's giant form after Kamek's spell in Bowser's Castle.

They show their teeth, like a Banzai Bill, but in a less menacing way. Additionally, their eyes are less menacing as well. Interestingly enough, the King Bill's eye pupils actually follow Mario's movements.

There is a total of 7 King Bills in New Super Mario Bros. Wii, all of them appearing exclusively in the aforementioned level: 9-8.

Trivia

 * The Prima Player's Guide for New Super Mario Bros. Wii erroneously referred to the Banzai Bill as a King Bill.