Sonic the Hedgehog is a video game series and media franchise created and owned by Sega. The franchise follows Sonic, an anthropomorphic blue hedgehog who battles the evil Doctor Eggman, a mad scientist. The main Sonic the Hedgehog games are platformers mostly developed by Sonic Team; other games, developed by various studios, include spin-offs in the racing, fighting, party and sports genres. The franchise also incorporates printed media, animations, a 2020 feature film, and merchandise.
The first Sonic game, released in 1991 for the Sega Genesis, was developed after Sega requested a mascot character to compete with Nintendo's mascot Mario. Its success helped Sega become one of the leading video game companies during the 16-bit era of the early 1990s. Sega Technical Institute developed the next three Sonic games in addition to Sonic Spinball (1993). After a hiatus during the unsuccessful Saturn era, the first major 3D Sonic game, Sonic Adventure, was released in 1998 for the Dreamcast. Sega exited the console market and shifted to third-party development in 2001, continuing the series on Nintendo, Xbox, and PlayStation systems.