Sega Corporation is a Japanese multinational video game and entertainment company headquartered in Shinagawa, Tokyo. Its international branches, Sega of America and Sega Europe, are headquartered in Irvine, California and London, respectively. Its division for the development of both arcade games and home video games, Sega Games, has existed in its current state since 2020; from 2015 to that point, the two had made up separate entities known as Sega Games and Sega Interactive Co., Ltd. Sega is a subsidiary of Sega Sammy Holdings. From 1983 until 2001, Sega also developed video game consoles.

Sega was founded by American businessmen Martin Bromley and Richard Stewart as Nihon Goraku Bussan on June 3, 1960. Shortly after, the company acquired the assets of its predecessor, Service Games of Japan. In 1965, it became known as Sega Enterprises, Ltd., after acquiring Rosen Enterprises, an importer of coin-operated games. Sega developed its first coin-operated game, Periscope, in 1966. Sega was sold to Gulf and Western Industries in 1969. Following a downturn in the arcade business in the early 1980s, Sega began to develop video game consoles, starting with the SG-1000 and Master System, but struggled against competitors such as the Nintendo Entertainment System. In 1984, Sega executives David Rosen and Hayao Nakayama led a management buyout, with backing from CSK Corporation.

In 1988, Sega released the Sega Genesis console (known as the Mega Drive outside North America). The Genesis struggled against the competition in Japan, but found success overseas after the release of Sonic the Hedgehog in 1991 and briefly outsold its main competitor, the Super Nintendo Entertainment System, in the U.S. Later in the decade, Sega suffered several commercial failures such as the 32X, Saturn and Dreamcast consoles. In 2001, Sega stopped manufacturing consoles to become a third-party developer and publisher, and was acquired by Sammy Corporation in 2004. In the years since, Sega has been more profitable. Sega Holdings Co. Ltd. was established in 2015; Sega Corporation was renamed Sega Games Co., Ltd., and its arcade, entertainment and toy divisions separated into other companies. In 2020, Sega Games and Sega Interactive merged and were renamed Sega Corporation.

Sega has produced several multi-million-selling game franchises, including Sonic the Hedgehog, Total War, and Yakuza. Sonic, Sega's mascot, is internationally recognized. Sega is one of the world's most prolific arcade game producers, with long-running series such as Virtua Fighter and Initial D Arcade Stage. Its name and branding are used for affiliated companies that operate amusement arcades and produce other entertainment products, including Sega Toys; however, these are largely separate ventures. Sega is recognized for its video game consoles, creativity and innovations. In more recent years, it has been criticized for its business decisions and the quality of its creative output.