Captain Ginyu is the leader of the Ginyu Force as well as being the strongest fighter on the team with a power level of 120,000. He possesses the unique ability to switch bodies when he encounters a stronger opponent (in reality, he transfers his mind into the opponent's body and vice versa). While strong, he was outdone by Goku, and he changes into the Saiyan's body after purposefully injuring his own. After changing bodies he realizes he cannot use Goku's body to its full potential. When he sees Vegeta is even stronger he allows himself to be badly beaten, before accidentally landing back into his own body. He's further tricked when Goku throws a frog between he and Vegeta, trapping him in an amphibian's body with no voice to transform.
His name is a play on gyū'nyū, or milk. The pun carries over into the team name as well as his attack in the Budokai series, Milky Cannon.
It has been stated that Ginyu has used the Body Change technique numerous times in his career, and that his humanoid appearance in Dragon Ball Z is the result of a previous Body Change, rather than Ginyu's original shell.