Buck was an extremely powerful altered 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.
After the ape uprising at the facility, Buck was ordered by Caesar, with a group of chimps, to free the apes held at the San Francisco Zoo. In the climactic Battle on the Golden Gate Bridge, Buck set his target on a nearby policeman on horseback. He ran up under the horse, lifting it up. This caused the officer to fall off. Buck approached the policeman and prepared to kill him, but Caeser stopped him. He later led some other gorillas in a charge to push an overturned bus along the bridge, to shield them against police bullets. He also helped throw off a policeman who drove his car in reverse to the sideline of the bridge into the ocean from shooting off the apes with his pistol. As Caesar was about to get shot down by Steven Jacobs and a sharpshooter in a helicopter, Buck sacrificed his life to take down the helicopter, which crashed onto the bridge, killing the occupants, but got repeatedly shot in the process. Caesar was saddened to lose his friend and his death was avenged by letting Koba finish off Jacobs.
Rise of the Planet of the Apes
Not much is known about Buck only that he was inmate at the San Bruno Primate Shelter along with Maurice, Rocket, Cornelia and Caesar. He was noted to be the only ape never harassed by Dodge Landon and was always kept in his cage isolated from the other apes and never once being allowed out causing him to feel lonely at being unable to interact with his own kind. He is first seen screaming at Caesar when he goes into the play den with the other apes on his second day at the shelter. Later on, he is shown screaming at another ape while trying to break out his cage by banging on the doors non-stop, his actions caught the attention of an observing Caesar who took an interest in the gorilla. On that same night, Caesar who learned how to pick locks escaped his cage before sneaking into the play den and opening a sleeping Buck's cage. Caesar woke him up by touching the gorilla's back, causing Buck to wake up screaming at Caesar whom he prepared to attack on the spot. However, Buck soon realized his cage was opened and though hesitant to walk out he quickly dashed out the cage rolling around in the straw in the den, playing with the toys the other apes played with over the years before letting out a large roar. Truly happy and grateful to be free, he turned and thanked the smiling Caesar and grew to respect him as a friend and alpha. Caesar then lured Rocket to the den and with Buck's help he overthrew Rocket as the alpha and took up the mantle of alpha of the shelter. Buck is later seen eating a cookie and howling with other apes after Caesar chose to stay at the shelter instead of leaving with Will Rodman. At night, Caesar would expose the apes to the ALZ-113 drug which would increase their intelligence there is no doubt he exposed Buck to the drug as the gorilla was shown to have green eyes the next morning.
When Caesar rebelled against Dodge, Buck paid witness to their confrontation and grew agitated as he saw his friend being shocked by Dodge's cattle prod. But when Caesar held off Dodge and spoke (in English) saying "No!" Buck was utterly shocked and speechless along with their human caretakers as Caesar knocked out Dodge and continued to saying "no" at the cattle prod. Caesar would then free all the other apes from their cells including Buck and the apes would leave the shelter and head for the city. Arriving at the outskirts of the city, Caesar divided his forces into two groups to Buck and some troops are too head for the San Francisco Zoo while Caesar, Rocket and Maurice's group headed for Gen-Sys Laboratories. Once at the zoo, Buck terrorizes the area which made many of the humans flee in fear as Buck charged at them after spotting a chimpanzee cage that he knocked down and freed more of his ape brethren who gladly followed the army's cause. Buck's actions at the zoo not only liberated more apes to his people's cause but had gave his people another contribution as when knocking down a cage the Evolved Apes use the bars as spears in their fight against the humans.
After gaining more apes, Buck led his people out of the area until they met up with Caesar's group that had just freed more Evolved Apes from the Gen-Sys Laboratories making a full army whose number's were in range of hundreds that soon filled the streets of the city with complete chaos. With more apes in the army, Buck had became Caesar's fourth in command and the new leader of the army's gorilla forces. Later on, he and Maurice were in the city until they spot two police cars heading towards them while Maurice threw a sewer lid at one Buck had ripped a parking meter out of the ground and threw it at the other stopping both cars in their place. The two would then meet up with the others and join up with Caesar and Rocket on a trolley heading for the Golden Gate Bridge, the army's next target.
Once at the bridge, the apes scared off the people who were caught in traffic and began making their way to the center of the bridge. The people seeing nothing but wild apes causing a ruckus had the police arrive at the bridge to form a blockade in hopes of wiping out the apes before they caused more trouble. However, Caesar had anticipated this strategy and ordered his people to halt noticing the police riding on horses who were attempting to lure the apes to the shooters on the other side. Caesar then ordered new recruit Koba to lead some chimpanzees on the bridge high wires using the fog as cover while Maurice leads the orangutans and some of the chimpanzees from the bottom of the bridge. Afterwards, Caesar led the remainder of his army to the center of the bridge as the police riders attacked them but Caesar knocked one down and had Buck join him. Buck then attacked a rider and while taking many blows from his baton he threw the rider to ground and was about to kill him however, Caesar told him "No!". With that Buck instead growled at the human's face before pushing him to the ground and meeting up with the others. Caesar put his plans into action by having Buck and the gorillas use their strength to knock over and push a large bus in to the center of the bridge which turned out to be effective as the police had begun to shoot and the bus held off their bullets. Caesar riding on a horse emerged from the fog and had the apes attack the officers resulting in a serious battle with the apes catching the humans off-guard with their brute strength and intelligence. The battle ended when a police van with apes on top of it nearly stumbled off the bridge and Buck busting through it's back doors and throwing the officer off the bridge to his death. The remaining officers then fled the bridge as the ape army began to celebrate over their amazing victory over humanity. However, this quickly subsided as a police helicopter rose up and began shooting the army causing the apes to suffer serious casualties and injuries. On board the chopper was Steven Jacobs, Director of Gen-Sys Laboratories had the police target Caesar seeing him as the ape leader this forced him to head for cover in a police van where he took a chain and threw it at the shooter and Jacobs knocking them both down. But this caused the other shooter to go into action and put the alpha in danger. Luckily, Buck, who witnessed this, pushed Caesar out of the way and leapt at the helicopter while taking countless bullets to the chest. Nevertheless, he made it on board where he attacked the shooter and pilot causing the chopper to spiral out of control and crash into the bridge where a series of explosions occurred.
Caesar quickly ran to the downed helicopter and pulled a critically injured Buck out of the wreckage. Buck slowly dying and with only a few seconds to live, thanked Caesar for his friendship and passed on in the arms of a true friend. Caesar closed Buck's eyes and gently laid his body down and started to grieve over the loss of his very dear friend. As this was happening, Caesar heard a voice cry out for help. Walking to the wrecked helicopter Caesar discovered a still alive but wounded Jacobs barely hanging over the ledge of the nearly off the bridge chopper. Jacobs begged Caesar for help and at first he was considering to, but his hatred of humans like Jacobs; who have abused, oppressed, and mistreated apes, and the loss of his friend told him not, to so he pulled his hand back and nodded at Koba to do what he wanted with the human. Koba knocked the helicopter off the bridge with his foot and sent a screaming Jacobs hurtling to his death, thereby avenging Buck's heroic death.