The Hammer Bro first made a splash in the original Mario adventure, Super Mario Bros. alongside his twin, jumping up and down between three platforms and throwing huge mallets.
What started as a silent bit part alongside other Super Mario Bros. baddies like Blooper, Goomba and the Piranha Plants, the Hammer Bro corralled the success of his first venture into supporting roles in the third Mario platformer, Super Mario Bros. 3. He has appeared in most of the other Mario entries since. He may not get the biggest roles in the Mario titles but it's hard to make a game without him. Recently, he's appeared solo, no longer needing to rely on being part of the identical team onscreen and in-game. But there is one co-star he will never be seen without, his namesake, the hammer.
He's been an enemy in Mario's SNES RPG outing, Super Mario RPG, played baseball and soccer, and been a fixture of the Mario Party series since it's inception.
Super Mario Bros 3 was the first appearance of a Hammer Bro variant called the Boomerang Bro. Instead of the traditional hammers, he would throw a boomerang. They appeared solo or in pairs in special bonus stages; defeating the boomerang bros in those stages would yield a special powerup for Mario's inventory.
Super Mario World introduced the Sumo Bro. Sumo Bros were a super-sized cousin of the Hammer Bros. They could jump up and make the ground tremble when they land. If they used this attack on a high platform, it would cause sparks to fall down and burn the ground.