Bombshell Bill

Bombshell Bills are enemies featured in both Paper Mario and Paper Mario: The Thousand-Year Door.

Paper Mario
Like the standard Bullet Bill, when Mario is in the overworld, he finds Bill Blasters that shoot these things out at Mario and crew. These, however, are much stronger, golden Bullet Bills. These enemies appear only in the final dungeon of the game as well, Bowser's Castle. They're also only in one room of the large fortress. These enemies are launched out of Bombshell Bill Blasters. Like the bullet bill, upon their attack, they automatically die, revealing a Star Point or two.

Paper Mario: The Thousand-Year Door
In TTYD, these bullets act the same way. These speeding dangers are launched from Bombshell Bill Blasters as well. Unlike their appearance in the previous game, however, they have attained some defense points, making them a little more difficult to defeat before they attack. They are also found only in the final dungeon in the game, this one being the Palace of Shadow.