Buck was an extremely powerful evolved gorilla housed in a specially built cage at the San Bruno Primate Shelter. He was notable for being the only ape to never be harassed by Dodge Landon. He was bad tempered, strong and brave, and was seen trying to get out and banging his cage. He was freed by Caesar and at first refused to go out, but after a few seconds Buck quickly dashed through the play area and begin playing with the toys the other apes played with. He respected Caesar and became his friend and his "muscle", even helping Caesar to make Rocket step down as alpha respect Caesar for his intelligence.