Optimus Prime

Optimus Prime is the leader of the Autobots. Once, long ago, he was a co-ruler of Cybertron together with his brother, Lord High Protector Megatron, but Megatron grew greedy and attempted to claim the All Spark for himself. Optimus rose to stand against him. As obsessively as Megatron strives to achieve his objective, Optimus is equally as dedicated to stopping him, even at the cost of his life, his world, and—if necessary—his own people. It was on his order that the All Spark was jettisoned into space, dooming Cybertron to a slow death and his people to nomadism. The sacrifices he has made weigh heavily on his spark, but they must be done, for there is no other choice. He knows the ambitions that lurk in Megatron's spark, and they must never see the light of day. Lives must be kept free from the threat of Megatron's tyranny, no matter the cost.

A year after the battle in Chicago, Optimus and the surviving Autobots join Jerome-092 alongside The Avengers and the Earthrealm Defenders. Optimus serves as the second-in-command of the team of heroes.

Transformers
After arriving and scanning a Peterbilt truck, Optimus greeted Sam Witwicky and Mikaela Banes, introducing his men and explaining why they had come to Earth. They escorted the humans back to Sam's house to retrieve the pair of glasses that would lead them the Allspark. When Sam and Mikaela were captured by a Sector 7 agent named Simmons, Optimus intercepted their car and surrounded the Sector 7 agents, curious that Simmons was not afraid or surprised by their appearance. When backup arrived, Optimus took the teens on his back and ran, taking cover under a bridge. Though Sam, Mikaela, and Bumblebee were captured, Optimus retrieved the glasses and prepared to lead his other men to get the Allspark, pointing out that, if it came to it, he would sacrifice himself by shoving the cube into his chest to prevent he Decepticons from getting control of the Allspark. When they discovered Bumblebee and the humans were free and being escorted by the military with the Allspark, Optimus joined their convoy. Along the way they, are attacked by Bonecrusher. Optimus engages him, killing him by using his Energon blade. Arriving in the city, he briefly confronted Megatron, but was left stunned. When he recovered, he rescued Sam as he was falling from a building and warned him that if he could not defeat Megatron before going into battle, he needed to place the Allspark in his chest. Optimus is nearly defeated by Megatron before Sam kills the Decepticon by ramming the Allspark into his chest. Optimus is grateful to Sam for saving him, and he and the other surviving Autobots decide to remain on Earth since Cybertron cannot be restored without the cube.

Transformers: Revenge of the Fallen
Optimus Prime leads the Autobots as part of NEST in seeking and destroying remaining Decepticons on Earth. At the beginning of the film, the massive Decepticon, Demolishor, is rampaging through Shanghai, China, and Optimus parachutes out of a plane to take him on. Before he is killed, Demolishor tells them that the Earth is "not theirs to rule" and that "the Fallen shall rise again". At the NEST base, Optimus tells Theodore Galloway that they do not know what The Fallen is and that if they are asked to leave Earth, the Autobots will comply. When the remaining Allspark shard is stolen, Optimus asks Sam for his help in convincing the Earth's leaders to allow the Autobots to stay, but Sam refuses. When Megatron is resurrected and Sam, Mikaela and Leo Spits are kidnapped, Optimus and Bumblebee attack the Decepticons holding them. Optimus fights Megatron, Starscream, and Grindor on his own to protect Sam in a forest. Though he manages to kill Grindor and rip Starscream's arm off, Optimus is ultimately killed by Megatron. His last words were for Sam to run. His body is taken to a military base where Galloway orders the Autobots to bring his body back to Diego Garcia. Meanwhile, Sam hears from Jetfire that "The Fallen" is an ancient Prime and that only a Prime could kill him. He also said that the Matrix of Leadership may be able to revive him. After a long battle with the Decepticons in Egypt, Sam resurrects Optimus using the Matrix, but it is subsequently stolen by The Fallen. Because Optimus is still weak, Jetfire offers to sacrifice himself to help. Ratchet and Jolt convert parts from Jetfire into a jet mode for Optimus. Optimus flies over to the pyramids and destroys the Sun Harvester. After severely damaging Megatron, he kills The Fallen, forcing Megatron and Starscream to retreat.

Transformers: Dark of the Moon
Optimus receives his own armory consisting of weapons and flight tech that transforms into a trailer for him to carry in vehicular form. After assisting NEST operatives in fighting Shockwave at Chernobyl, Optimus learns that the humans have concealed the discovery of a Cybertronian ship on the moon. He and Ratchet go to investigate the Ark, where they recover Sentinel Prime, Optimus's predecessor and mentor. Optimus returns him to life using the Matrix of Leadership back on Earth, explaining how they lost the war and Cybertron has become a barren wasteland. Later Optimus shows Sentinel the natural beauty of Earth, and takes the opportunity to offer him the Matrix, but was allowed to keep it. Sentinel later betrayed the Autobots, having formed an alliance with the Decepticons because he wants to restore life to Cybertron. Optimus attempted to reason with Sentinel, but failed as several Decepticons came through a space bridge. After Sentinel Prime insisted that the humans expel the Autobots from Earth, the Wreckers prepare the Autobot ship Xantium for flight. Sam attempts to find out what their counter-attack plan is, but Optimus states they have none, and that Earth's fight is their own. During the departure, the Autobots escape in the first booster stage and return to Earth before Starscream destroys the ship. Arriving in Chicago, Optimus shoots down a Decepticon fighter as he tells Sam and Epps that he never expected the Decepticons to keep their word and that they are going to fight back. Optimus loses his trailer when Shockwave and his Driller arrive. He manages to retrieve it later and uses it as a flight pack, decaptitating the Driller's main head. During the battle, Optimus got caught in exposed wires and the Wreckers helped free him. Flying down onto the main battlefield, he abandoned his flight pack and used the momentum to attack and kill many Decepticons before he finally killed Shockwave. After using Shockwave's cannon to disable the control pillar for the space bridge, Optimus fights Sentinel Prime. Optimus Prime's right arm is cut off and Sentinel is about to end Optimus's life when Megatron intervenes and attacks Sentinel. After defeating Sentinel Prime, Megatron proposes a truce, but, instead, Optimus slices his head off, killing the Decepticon leader. Optimus Prime then grabs Megatron's shotgun and prepares to execute Sentinel, who pleads for his life, saying that he betrayed Optimus just because he wanted to save their race. Optimus executes him anyway, replying that Sentinel betrayed himself. With the Decepticons defeated and the reign of Megatron being over, Optimus and the Autobots accept Earth as their true home.

The Last On Earth
Optimus Prime will return in The Last On Earth.