Hammer Bros. are a sub-species of the average Koopa Troopa which are found throughout Mario's travels. Originating in the first Super Mario Bros. for the NES, these nefarious Koopas will lob hammers in an arch at Mario. They are said to be some of Bowser's most elite troops and pose a great threat in various Mario titles today.

Appearance: Hammer Bros appear in the same general style as Green Koopa Troopas. Their shell, however, has white lines in all the little cracks and crevices, and their eyes are not the highest point on their body. They have the same mouth/ beak as a normal Koopa Troopa; however unlike their common cousin, their eyes are blue and not just black. They also wear helmets atop their heads, perhaps to protect from hammers. These helmets however, do not protect against a stomp from Mario. In older Mario games they were not shown to wear boots, but in more recent Mario titles they do indeed have green boots on their feet.

How to defeat them: A jump on the head is all it takes to take care of a Hammer Bro. However, this is not easy to achieve, due to them constantly hurling hammers in Mario's direction. Since they are usually found jumping between two rows of brick blocks, it is possible to jump under the block the Hammer Bro. is on and get rid of them this way. They can also be frozen by iceballs and tossed or shattered, burnt by fireballs, hit with a tail by Raccoon Mario, and bulldozed by Invincible Mario. Tossing shells into them works too, as well as having Yoshi eat their hammer and spit it back at them. Whatever your preferred method of attack is, use it and these tough enemies will go down.

Trivia: There are multiple variants of the normal Hammer Bros., such as Fire Bros, Ice Bros. and the Amazing Flyin' Hammer Bro.

Hammer Bros. appear in a 3D Mario game, which isn't a spin-off title, for the first time in Super Mario Galaxy 2, accompanied by their cousins, the Boomerang Bros.

A Hammer Bro. appears in Super Smash Bros. Brawl as an assist trophy.