Buck was an extremely powerful evolved western lowland 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 due to his size and strength, which forced John Landon to keep Buck in a reinforced cage at all time. He was freed by Caesar and at first refused to go out, as he begin playing with the toys the other apes played with. He respected Caesar and became his friend and his enforcer, even helping Caesar to make Rocket step down as alpha. After the ape breakout, Buck took part in liberating other apes and fought alongside Caesar. During the climax of Battle on the Golden Gate Bridge, Buck sacrificed himself to protect Caesar.