Boomerang Bro

Boomerang Brothers, also known as Boomerang Bros., are relatives of the Hammer Bros.. However, instead of wielding Hammers, they wield boomerangs, as their name implies. They can be defeated just the same as regular Hammer Bros. In Super Mario Bros. 3, some Boomerang Bros. had risen to high ranks within Bowser's forces and were given command of tanks and other war vessels.

Boomerang Bros. occasionally appeared as sub-bosses in the game Yoshi's Safari. In these battles, Mario is able to shoot their approaching boomerangs with his Super Scope to avoid being hit.

Some (really thin) Boomerang Bros. with sunglasses and sprouts on their helmets live in Gwarhar Lagoon, as seen in Mario and Luigi: Superstar Saga. As seen in Paper Mario: The Thousand-Year Door, one Boomerang Bro. resides in Glitzville, where he fights for the team: Hamma, Bamma, and Flare. This Boomerang Bro. (the only one in the game) is named Bamma.

A Boomerang Bro. (blue-shelled) was playable in Mario Superstar Baseball as a palette swap of Hammer Bro. (green-shelled), once he's unlocked. He also appeared on the Bowser Monsters team in Challenge Mode.

They also appeared in New Super Mario Bros., throwing boomerangs as always. They appeared only in two levels.

Originally, Boomerang Bros. were green and wore Hammer Bros.' armor. Now they're normal colored (for a Koopa) and wear a blue version of the Hammer Bros. armor.

Cartoons
Boomerang Bros. also appeared several times in The Adventures of Super Mario Bros. 3, serving as soldiers in Bowser's army. Through the use of their boomerangs, Boomerang Bros. were practical in long range attacks. Unlike in the game, it was not uncommon for Boomerang Bros. on the show to travel together in groups.

Comics
A Boomerang Bro. made a relatively minor appearance in Nintendo Comics System issue "The Kingdom Inquirer", which had one appearing to attack Mario and Toad with it's boomerangs after the two exit a Warp Pipe.