|Status||Captured and Sealed by Akatsuki|
The Four-Tailed Monkey, or Son Goku (The name given by the Sage of Six Paths), is one of the nine Bijuus. It has made little appearance in Naruto.
Madara Uchiha claims that long ago the Sage of the Six Paths saved the world from the Ten-Tailed Beast and became it's jinchuriki. Before he died, he divided the beast into the Nine Bijuus. Roshi was briefly seen unconscious on the back of Kisame the one who supposedly captured it single handedly.
Son Goku was seen again when revived with it's jinchuriki by the Edo Tensei in the Fourth Shinobi World War. He was seen fighting with Bee and Naruto. During the fight, Son Goku swallowed Naruto and for yet released reason, Naruto was able to go inside the Four-Tailed and talk to the bijuu himself.
Like the other bijuus it is assumed it has enormous amounts of chakra, brutal strength, and the ability to form the Tailed-Beast Ball.