Hammer Bro

Hammer Bros. are enemies from the Mario franchise, and they are Koopas who throw hammers at other characters. Their first appearance in a Super Smash Bros. game is Super Smash Bros. Brawl (not including the first two games, where they only cameo in the background of each game's Mushroom Kingdom stage). A Hammer Bro appears as an Assist Trophy in every Super Smash Bros. game from Super Smash Bros. Brawl onward.

Background information
Hammer Bros. first appear as enemies in the Nintendo Entertainment System game, Super Mario Bros. and would appear in most later Super Mario 2D installments. In the games, Hammer Bros. attack Mario or Luigi by throwing hammers at them. Hammer Bros. can jump high, allowing them to reach a higher platform before dropping back to the platform or ground beneath.

On July 2, 2007, the Smash Bros. DOJO!! revealed Assist Trophies and a Hammer Bro as one of their characters for the then-upcoming Super Smash Bros. Brawl. The post has three screenshots, all of which take place in the Delfino Plaza stage, that demonstrate the use of an Assist Trophy. The first image shows Kirby holding up an Assist Trophy, then the second image shows a close-up of a Hammer Bro, and the third screenshot shows that Hammer Bro throwing a hammer at Fox.

Super Smash Bros. Brawl
In Super Smash Bros. Brawl, aside from being an Assist Trophy, Hammer Bros. are enemies in some The Subspace Emissary levels, in order of The Jungle, The Lake, The Cave, The Swamp, and lastly The Great Maze. Hammer Bros. are the only character in Super Smash Bros. Brawl to be both an Assist Trophy and an enemy in The Subspace Emissary. In the opening cutscene of The Jungle, a Hammer Bro is seen loading bananas onto the cargo. The Hammer Bros. in The Subspace Emissary act the same as their Assist Trophy counterpart, but can be attacked and defeated. The player earns 500 points for each Hammer Bro that their fighter defeats.

There is a Hammer Bro sticker, which reuses its New Super Mario Bros. artwork. There is also a Hammer Bro trophy, which mentions New Super Mario Bros. as one of its appearances. The Hammer Bros. were designed after their New Super Mario Bros. appearance and other Mario spinoff titles released around that time.