Bullet Bill

Bullet Bills are a missile-like enemies in the Mario series that are shot from a tall standing shooter called Bill Blasters. A Bullet Bill usually follows a straight direction until it gets destroyed or get off-screen. A stronger variant known as the Heat-Seeking Bullet Bill, follows the player until it can hit him; it can be differentiated from a regular Bullet Bill because its eyes flash in a red color.

In Super Smash Flash 2
Bullet Bill posibly makes the appearance in the Adventure Mode of SSF2, and SSF2 DOJO!!! confirm it.