Bullet Bill (enemy)
Bullet Bills are common enemies in the Mario series, debuting in Super Mario Bros.. They quickly fly in a straight line, damaging the player on contact, and like most enemies they can be defeated by simply jumping on them. They are most commonly shot by Bill Blasters, though in rare cases they appear on their own. In later games, homing and bigger versions were introduced.
Bullet Bill was mentioned in the Banzai Bill trophy.
The Bullet Bill commonly appears as an enemy in The Subspace Emissary. They fly from offscreen, exploding upon impact with a character or on the ground. They also appear in Donkey Kong and Diddy Kong's introduction, in which three of them are destroyed by Diddy Kong. They can be reflected, but will often quickly recover and continue their attack. Some of them are homing, following players until they hit. Unlike in the Mario games, Bullet Bills cannot be defeated by jumping on them.
Bullet Bills appear as enemies. They retain their homing behavior from Brawl, though they can no longer be reflected. They deal 3% damage upon impact, or more if they collide with a surface and explode. In addition to being found on their own, they can also be fired from Bill Blasters, in which case they do not home in on the player.
A large number of Bullet Bills can appear as a random event.
Bullet Bills appear as part of the Mario-themed Vs. Enemy Team final battle, where some of them fly forward like as if they were shot out of a Bill Blaster rather than homing in on the player.
The Bullet Bill returns as an item, retaining the same functionality as in Smash 4. It also appears as a spirit.