Boom Guy
Full Name Boom Guy
First Appearance Mario and Luigi: Partners in Time
Species Shy Guy
Affiliation(s) Baby Bowser, Koopa Troop

A Boom Guy is a red Shy Guy that balances a Bill Blaster on top of its head. They have 18 HP total. During the events of Mario & Luigi: Partners in Time, Boom Guys patrolled the halls of Baby Bowser's Castle. Upon spotting an intruder, a Boom Guy would fire a Bullet Bill, engaging the intruder in battle. In a fight, a Boom Guy fires Bullet Bills to attack, an attack that can be dodged by jumping. The Boom Guy may also try to trick its opponent by firing a puff of smoke before he actually attacks. This can be predetermined by looking if he points at Mario or Luigi before attacking. If Boom Guys are weakened enough to the point where its cannon falls off, it will start to panic. Without a cannon, a Boom Guy can only call for help. If heard, two Fly Guys will appear and drop another Bill Blaster on the Boom Guy's head, allowing the Boom Guy to resume the fight. If not heard, the Boom Guy will continue to panic.

A stronger variety of this foe exists, only that it is colored blue, fires faster bills, has overall almost five times the stats that a regular Boom Guy has, and takes more hits for its Bill Blaster to fall down.