also known as the Turtle Hermit (亀かめ仙せん人にん Kamesen'nin) and God of Martial Arts (武道の神様 Budō no Kamisama), is a master of martial arts, who trained Gohan, Ox-King, Goku, Krillin, and Yamcha. He has a sister named Fortuneteller Baba. He is also a hermit and a pervert.

Roshi cares deeply for his students to the point he entered the World Martial Arts Tournament in the guise of a martial named "Jackie Chun" to ensure they would lose the tournament as he felt they might lose interest in the martial arts if they won it too easily due to the great strength they had obtained through his training. While this may have been true for a fellow Earthling martial artist like Krillin, Roshi was unaware that Goku was actually a Saiyan who would never lose interest in fighting due to the Saiyan's inborn love of fighting until many years later after the arrival of Raditz, though through a story he heard from Goku's Grandpa Gohan he did known that Goku was the elder Gohan's adoptive grandson and may have suspected the boy's potential alien origins from the story Gohan told him. As a result, Roshi found a tough opponent in the young Saiyan and it took all of his skill, power, and abilities to defeat Goku during final match of the tournament. Also during the tournament he showed compassion to Nam by explaining he did not need the prize money to buy water after he was defeated by Goku and gives him a capsule to store water from a well, although in exchange for his help Roshi asks Nam to help him protect his secret identity from his students by having him impersonate Master Roshi in the audience and convince his students that Jackie Chun and Master Roshi were separate people. He is also shown to be quite intelligent as he managed to figure out the Moon was the cause of Goku's Great Ape transformation and correctly deduced that destroying it would cause Goku to return to normal and prevent any further transformations (Piccolo would later use this very same tactic in Dragon Ball Z to stop Gohan's transformation in the Vegeta Saga as well as prevent Nappa and Vegeta from using the Moon to transform). Despite his skirt-chasing antics, Master Roshi is still a very wise and kind-hearted person who loves those around him like his own grandchildren. He openly enjoys life and its simple pleasures, but is willing to die for an honorable cause if necessary. Despite being immortal Roshi dies when attempting to utilize the Evil Containment Wave against King Piccolo (who was freed during the King Piccolo Saga), which shows that his immortality only prevents him from dying from old age and thus is not completely immortal. He appears in most of the Dragon Ball and Dragon Ball Z movies, usually as comic relief, though in The World's Strongest and Resurrection ‘F’ he actively participates in the fight alongside the other Z Fighters.