Hammer Bros. (also called Hammer Brothers; called Hammer Bros in many games) are a species of Koopa that stand upright and throw hammers at passers-by. They first appeared in the game Super Mario Bros.. They have bigger shells than normal Koopas and wear headgear, most likely to protect themselves from their hammers. They can also use special hammers to shrink their enemies. Hammer Bros have many times been described as the most elite fighters in Bowser's Koopa Troop. These enemies were originally designed by Kazuaki Morita.