Namu is a Buddhist monk who first entered the martial arts spotlight at the 21st Tenka-ichi Budōkai. He beat Ran Fuan in his opening match—though not without some awkwardness on his part when she stripped down, given his religious vows. His real test came against Son Goku, an intense fight he ultimately lost.
Namu had competed out of necessity rather than glory-seeking. His home region was suffering from a severe drought, and he'd been tasked with finding water. The tournament prize money was meant to help him buy enough to bring back. After his loss, he was stuck until Muten Roshi, reading his mind and recognizing his plight, gave him a capsule for water storage from a well. In exchange, Roshi asked him to pose as himself in the crowd during the tournament—a cover story to throw off his suspicious students who were already questioning whether Chun might actually be the old master.
Namu showed up again for the 22nd tournament (in an anime-only storyline), claiming he'd come just to watch this time around. That didn't pan out either—Tenshinhan knocked him unconscious and nearly killed him in the preliminaries, deliberately sending a message to Goku and his friends with the brutality.
Things got darker when Tambourine, one of Piccolo Daimaō's henchmen, killed him. Thankfully, Shenlong brought him back. He later contributed energy to Goku's Spirit Bomb and made a brief appearance in GT during the episode "Piccolo's Decision."
Fan theories occasionally link him to Uub, though nothing's ever been confirmed. His name derives from the Buddhist prayer "Namu Amida Butsu."
Content compiled by AnimeList.moe from publicly available sources.