Hammer Bro

Hammer Bros. are a species of hammer-throwing Koopas in the Mario franchise. They first appear in Super Mario Bros.. Hammer Bros. are among the stronger enemies encountered by Mario and his friends, and are elite-ranked members of the Koopa Troop. Hammer Bros. are often encountered in pairs. They have several variants, such as the fireball-throwing Fire Bros. and the boomerang-throwing Boomerang Bros..

In an Iwata Asks, it is revealed that Hammer Bros. were created by Kazuaki Morita.

Super Mario Bros.
In Super Mario Bros., Hammer Bros. are found in a few levels, with World 3-1 being the first one that they appear in. Hammer Bros. are usually found on parallel platforms, guarding a small area, and they jump up and down and move back and forth while throwing a continuous supply of hammers at Mario or Luigi. If a Hammer Bro stays onscreen for too long without being defeated, it starts to chase them.

Super Mario Bros.: The Lost Levels
In Super Mario Bros.: The Lost Levels, Hammer Bros. appear in more levels, possibly owing to the game having a higher difficulty than Super Mario Bros.. The Hammer Bros. in the first six worlds retain their exact behavior from Super Mario Bros., although starting with World 7, any Hammer Bro that Mario or Luigi encounter instantly begin to slowly chase after them.

Super Mario Bros. 3
In Super Mario Bros. 3, Hammer Bros. return as an enemy, and the game also serves as the debut appearance of their first three variants, Fire Bros., Boomerang Bros., and the heavyweight Sledge Bros.. Hammer Bros. have a slightly larger role than in the previous two Super Mario titles. The game also introduces the Hammer Suit power-up, which allows Mario or Luigi to throw hammers just like a Hammer Bro.

Aside from appearing in levels, where they behave similarly as in Super Mario Bros., Hammer Bros., along with their variants, are also encountered on the overworld map, where they patrol back and forth on a certain marker. When Mario or Luigi step on to the same one, they are forced into an Enemy Course where they have to battle two Hammer Bros (one in the World 1 Enemy Course) or its variants, depending on the location. Whenever Mario or Luigi exits a location, including from losing an extra life, the Hammer Bro moves to a different marker on the map, although within a certain range. In an Enemy Course, after Mario and Luigi defeat both Hammer Bros., a treasure chest appears, containing a certain item that can be used from the world map. If Mario or Luigi use a Music Box on the overworld map, they can put Hammer Bros. and other overworld enemies to sleep. They wake up after Mario or Luigi have cleared a level or lost two extra lives.

The original Nintendo Entertainment System version uses the same overworld icon for Hammer Bros. and their variants, although the Super Mario All-Stars and Super Mario Advance 4: Super Mario Bros. 3 remakes give the Hammer Bro variants their own distinct overworld sprites.

Super Mario World
In Super Mario World, Hammer Bros., along with Sledge Bros., were originally to make another returning appearance. Although this did not occur, the game introduced another Hammer Bro variant, the Amazing Flyin' Hammer Brothers, and a distant relative, the Sumo Bros..

Dance Dance Revolution: Mario Mix
In Dance Dance Revolution: Mario Mix, two Hammer Bros. appear in level 3-1, where they guard the entrance to Wario's Carnival. Either Mario or Luigi must win in a dance-off against them before they are allowed to enter.