A box controller is a controller that is used to play Super Smash Bros. Perhaps the two main pioneers of the category are the Smash Box and B0XX.
The GRAM PRI$M allows you to play Smash and other titles ergonomically with a variety of possible layouts.
The Glyph is a modular all-button controller that is available in layouts for games from Smash to Street Fighter.
The Tadpole by Rana Labs is a mini Smash controller that sports the community's favorite layout plus an extra button on the upper left.
The Oblong is a mini rectangle controller that comes in different colors, but more interestingly, there is an extra button.
The FightBox R1 is FightBoxArcade's answer to the recent influx of box/rectangle controllers that are growing on the Smash community.
The GRAM Slim is one of the GRAM Digital Controllers, and it runs on the UMS Ultra Bubblebox WASD firmware.
The Superslab Digital Combat Controller is a smaller LED controller by Prong for Super Smash Bros players.
The Pinebox is a stickless controller that is made of pinewood and is also available in a Super Smash Bros layout.