Gigantopithecus

Gigantopithecus is believed to be the largest primate to have ever lived. Although quadrapedial, when standing on it's hind limbs, Gigantopithecus would have stood nearly ten foot tall and weighed around 1200 lbs. This prehistoric relative of modern orangutans lived between 1.3 and .3 MYA.
This reconstruction of the skull of Gigantopithecus was made by Grover Krantz. Krantz, a professor at Washington State University, was a proponent of the idea that Gigantopithecus was a bipedial ape, moving mostly on two legs.