Gilgamesh is the main character of the Epic of Gilgamesh, an Akkadian poem considered the first great work of literature. He is a demigod with superhuman strength who builds the walls of Uruk to defend his people and travels to meet the sage Utnapishtim, a survivor of the Great Flood.
Gilgamesh is believed to have actually existed by many scholars. It is estimated he lived sometime between 2800 and 2500 BC. The Sumerian King List claims Gilgamesh ruled the city of Uruk for 126 years.
Gilgamesh in Final Fantasy is also based on Benkei, a famous character in the Japanese mythologies and chronicles of the Genpei War. A powerful warrior monk said to have personally defeated 200 men in every battle he engaged in and said to have had the strength of demons, Benkei's introduction sees him set out to collect 1,000 weapons, and to this end he posted himself at Gōjō Bridge in Kyoto and challenged every warrior who attempted to cross. On his 1000th duel Benkei was defeated by Minamoto no Yoshitsune, the only defeat he had ever known, and became his faithful retainer throughout the rest of his life.
From the story of Benkei, Gilgamesh takes his preference for the naginata (Benkei's traditional weapon as a monk), his penchant for fighting on bridges, his collecting of weapons from enemies he defeats, and his friendship with the player's characters who defeat him. Benkei's devotion to Yoshitsune is the basis for Gilgamesh's association with Genji equipment—the Minamoto Clan is also called the Genji Clan, using the alternate pronunciation for the Chinese characters for mina and moto, gen and uji, respectively. Gilgamesh's face paint is based on traditional kabuki actors, for which Benkei is a popular character to portray.