Keiji Mutoh (武藤 敬司 Mutō Keiji, born December 23, 1962) is a semi-retired Japanese professional wrestler who first gained international fame in the National Wrestling Alliance (NWA). He is mostly known for his work as The Great Muta in New Japan Pro Wrestling (NJPW) during the 1990s, but he has also worked in United States, Puerto Rico, Mexico, and Taiwan. He is a former owner and president of All Japan Pro Wrestling (AJPW), as well as being a full-time wrestler for the promotion from 2002 to 2013. He also gained the rank of the Master Sergeant during his military service. Mutoh is credited as one of the first Japanese wrestlers to achieve a fan base outside of his native Japan in the United States.

The Great Muta gimmick is one of the most influential gimmicks in puroresu, having been emulated by many wrestlers including Satoshi Kojima (as The Great Koji), Kazushi Miyamoto (as The Great Kazushi) and Atsushi Onita (as The Great Nita). In addition, countless independent wrestlers have paid tribute to Muta through emulation and imitation. Mutoh is one of three wrestlers to hold the NWA World Heavyweight Championship, the AJPW Triple Crown Championship and the IWGP Heavyweight Championship (the other being Shinya Hashimoto and Satoshi Kojima). He is an eight-time World Champion, having held the NWA World Title once, the IWGP Title four times, and the AJPW Triple Crown three times. He also has held a dozen World Tag Team Championships in the U.S. and Japan.

Between NJPW, AJPW, and World Championship Wrestling (WCW), Mutoh has held 19 total championships. He is also famous for taking part in what is generally considered to be the bloodiest professional wrestling match of all time against Hiroshi Hase, leading to the creation of the "Muta Scale". Mutoh is currently the owner and founder of Wrestle-1, where he also wrestles semi-regularly.