Sega

Sega Corporation (, Kabushiki-kaisha Sega), officially capitalized SEGA, is a multinational video game software and hardware development company, and a home computer and former console manufacturer headquartered in Ōta, Tokyo, Japan, with various offices around the world. The company is famous for several notable game series, most notably, the Sonic the Hedgehog series. In the past, Sega was Nintendo's greatest rival. They even made anti-Nintendo campaigns, such as the old American marketing slogan for the Sega Mega Drive (Sega Genesis in America), which was "Genesis does what Nintendon't". The company had success with both arcades and home consoles, but on January 31, 2001, following poor sales of the Dreamcast and profit losses, Sega restructured itself and left the consumer console business to concentrate on software development for multiple third-party platforms. On 1st October 2004, they merged with a Japanese pachinko company called Sammy to form Sega Sammy Holdings, but still exist as a subsidiary of the company. The company is also famous for its SEGA! chant that appeared on both commercials and games.

In Super Smash Bros. Brawl
Sega was described as being in "special collaboration" with Nintendo regarding Sonic's inclusion in Brawl, where he and Solid Snake became the first third-party characters to appear in the series. Additionally, other characters from the Sonic franchise, such as Shadow, Tails, Knuckles, and Silver, have minor roles in Brawl, and the iconic Sonic level, Green Hill Zone, appears as a stage.

In Super Smash Bros. for Nintendo 3DS / Wii U
Sega's mascot returns as a third-party character in Super Smash Bros. 4. Additionally, Windy Hill Zone, a stage from their Nintendo (3DS/Wii U) exclusive Sonic Lost World, appears in Super Smash Bros. for Wii U, while Green Hill Zone returns from Brawl in Super Smash Bros. for Nintendo 3DS. Two costumes based on Akira Yuki and Jacky Bryant from Sega's Virtua Fighter series appear as downloadable content. In addition, Mii costumes based off Knuckles and Tails appear for the Mii Brawlers and the s, respectively.

from the Bayonetta series is another newcomer, available as DLC. She is Sega's second playable representative in Super Smash Bros.

Trivia

 * Sega and Square Enix are the only third-party companies to have a character represented in the Super Smash Bros. series but not in .
 * Sega is the second of two third-party companies to have multiple representatives in Super Smash Bros. 4, right after Capcom.