Oozaru Vegeta is the transformed state of the Saiyan prince, Vegeta, in the anime series Dragon Ball Z. When Vegeta looks at the full moon or an artificial moon and has his tail intact, he transforms into a gigantic, powerful ape called 'Oozaru.' In this form, he gains a massive boost in strength and size, becoming a formidable adversary for Goku and his allies during the Saiyan Saga. This transformation is a crucial part of Vegeta's role as a major antagonist early in the series.