A series of fighting games developed by Nintendo that include many of their most famous characters as fighters.
Smash Brothers differs from typical fighting games in that it's set on typical "platform action game" type stages.
Also, defeating a character is not done by depleting its health, but to knock the character out of the screen (or rather, playing area). Characters do take damage; the more damage they take, the "lighter" they become, and more liable to fly out of the screen should they receive a heavy punch. Having four players on the same screen in a battle royale is also typical for the series; the Japanese pre-title "Dairantou" means "big chaotic battle".
The series stared on the Nintendo 64, and has had one representation on each of Nintendo's big platforms evern since. The 3DS was the first of the handheld devices to get a Smash Brothers.
While the first game only contained Nintendo characters, more and more characters have joined the fray, most notable being perhaps the inclusion of Solid Snake from Konami's Metal Gear Solid in the Wii version, and the inclusion of Sega's Sonic, Capcom's Rockman (Megaman) and Namco's Pacman in the 3DS/WiiU version.