Oozaru is the giant ape transformation associated with Saiyans in Dragon Ball Z, not a distinct individual character. When a Saiyan with a tail looks at a full moon or similar Blutz Wave source, they can transform into this enormous, berserk ape form, gaining massive strength and destructive power. Oozaru is important in the series as a dangerous power-up and a key part of Saiyan biology and lore, especially in early Dragon Ball stories and flashbacks.