Turtle is a long time companion of Master Roshi who live together on a small island with the Kame House. Turtle is generally a very friendly and calm individual, though he tends to lose his temper when Roshi gets perverted with women.
Despite not appearing very often in the series, Turtle had major importance in the overall story. When Goku rescued him and took him to the ocean, Turtle returned with Master Roshi, whom would later become Goku's mentor.
In the anime, he is stated to be 1,000 years old.
As mentioned above, Turtle is very quiet and calm. The only times Turtle has really expressed anger is when Master Roshi gets too perverted with women and his dirty magazines.
Interestingly, despite appearing as a normal sea turtle, Turtle is able to speak.
He seems to have some honorable principles, as when he was offered a kiss by Maron, he withdrew into his shell, claiming he did not want to be distrustful to Krillin.
Abilities and powers
Though not normally a fighter, years of living with Master Roshi seems to have given Turtle some knowledge and experience in martial arts, as seen when he protects Krillen's then girlfriend Maron from two males who were trying to take advantage of her.