|Banzai Bill did not originate from fanon, and more information can be found on their respective wiki(s). You may read more about it on the following wiki(s):
Banzai Bills are a sub-species of Bullet Bill that first appeared in Super Mario World. Banzai Bills also have a sub-species called Missile Banzai Bills.
Banzai Bills return as enemies yet again in New Super Mario Bros. Omega.
Banzai Bill's have been confirmed to be appearing in the game Super Mario World: Wii as enemies.
Bonzai Bill with its tongue sticking out