Bullet Bill

Bullet Bills are black, missile-like enemies, commonly depicted as having small arms and fanged frowns on their faces; they first appeared in Super Mario Bros. They are usually fired by cannons known as Bill Blasters, although they are sometimes fired from other sources, such as Snifits and generic cannons. In Super Mario World they can sometimes just fly in from the edge of the screen, including the top and the bottom. Bullet Bills commonly appear as enemies or obstacles, attacking by either flying forward after being shot or actively seeking a target, either smashing into them then continuing movement or exploding on contact.