Sentinel Prime (Transformers Film Series)

"For Cybertron! For our home! What war destroyed, we can rebuild - but only if we join with the Decepticons!"

- Sentinel explaining why he must revive Cybertron

Sentinel Prime is the main antagonist of the 2011 film Transformers: Dark of the Moon. He can transform into an airport fire truck. The Prime was originally an Autobot, the original Autobot leader before Optimus and taught him the values of life and honor to the end. He was the most powerful Autobot in existence before his death at the hands of his pupil-Optimus Prime. He betrayed the Autobots and became a Decepticon; so that he could save Cybertron. The movie's title Dark of the Moon is a reference to him and his space bridge pillar technology that forms the plot. Sentinel's ruthless motives and selfishness towards both Optimus and Megatron led to his own death.

Sentinel Prime is known for being the only villain in the live-action Transformers franchise in which Optimus Prime was never able to defeat alone, even with his best efforts. (Technically, Optimus never defeated any of the main antagonists in each movie alone: in Transformers he defeated Megatron together with Sam Wiwicky and the human soldiers. In Revenge of the Fallen, he defeated The Fallen with Jetfire's sacrifice (Jetfire killed himself in order to let Optimus take his parts to make him powerful enough to fight The Fallen). And in Age of Extinction, he defeated Lockdown together with Bumblebee and Cade Yeager, though he was able to kill Harold Attinger alone.)

He was voiced by the late Leonard Nimoy, notable for being Mr. Spock in Star Trek. Nimoy also voiced Galvatron in The Transformers: The Movie, first released in 1986, and also appeared in Transformers 2007 (we hear him as Mr. Spock on Bumblebee's faulty speech generator) & also the voice of Master Xehanort in the Kingdom Hearts series.

Past
On the Planet Cybertron, there was a great war that practically destroyed Cybertron. Wanting to save his dying homeworld, Sentinel Prime previously made a secret pact with Megatron to help him recreate Cybertron in the name of the Decepticons. Megatron told him to take his Space Pillars (machines that can teleport anything) to the planet Earth and they'll recreate Cybertron there. Sentinel Prime flew away in a ship called the Ark that carried hundreds of Space Pillars. Sentinel Prime was suppose to warp jump to Earth so he and Megatron could recreate Cybertron. However, before he could warp jumped, Decepticon airships dealt heavy damage towards the Ark, resulting in Sentinel Prime to accidentally crashed landed on the dark side of the moon. This also resulted in Sentinel Prime entering in stasis lock.

In 1969, Neil Armstrong was secretly assigned to search on the moon and analyzes the crash. Armstrong claimed there were no survivors. Since 1972 no one went to the moon since, and was deemed above classified. Neil Armstrong decided to take the space bridge pillars from the moon, which were then stored in secret by the government which became a law that no one is to know of the alien technology. This law was enforced by the arrogant Director of National Intelligence, Charlotte Mearing before Sentinel was revived.

Present Day
When Optimus Prime and Ratchet were helping their human allies, they encountered a piece of a machine that was originally part of the Ark. They eventually discovered that the Ark crashed landed on the dark side of the moon. The Autobots flew to the dark side of the moon and found the Ark, along with both Sentinel Prime, and five Pillars. With the Autobot Matrix of Leadership, Optimus revived Sentinel Prime. Sentinel took the form of a Rosenbauer Fire Engine. When Sentinel Prime and Optimus Prime were talking to each other alone, Optimus thought that since Sentinel Prime was his leader, Sentinel should have the Autobot Matrix of Leadership and continue leading the Autobots. However, Sentinel said that since he knows nothing about this planet, Optimus should keep the Matrix, teach him about the Planet, and continue being the leader of the Autobots.

Betraying the Autobots
The Decepticon sub-group trio, the Dreads (Hatchet, Crowbar & Crankcase) chased after Sentinel Prime. Bumblebee, Dino, Ironhide and Sideswipe guarded Sentinel allowing him to escape wherein Bumblebee & Dino killed Hatchet while Ironhide and Sideswipe kill off Crankcase & Crowbar. After the chase scene ended Sentinel revealed his intention, claiming that the Autobots shall realize that Sentinel was not actually going to help the Autobots win the war, but instead turn against them and explained he made a deal with Megatron. Before anyone could react, he murdered Ironhide, the Autobot closest to him, with his Cosmic Rust gun, and wiped out NEST, with only a few human survivors.

The Invasion and Usurping the Decepticons
With the help of Megatron, Starscream and other Decepticons, they were able to open a space gate so the Decepticons can invade Earth. He decided to spare Optimus, because he was his apprentice once, and he wanted Optimus to watch the fall of the human race. They first took over Chicago and that if anyone tried to infiltrate they would be killed. They also killed most of the people who lived in Chicago (except of Dylan Gould for being an ally and Carly). But while the space bridge pillars where being set up, Sentinel Prime attacked Megatron and reminded him of his place: Sentinel did not work "for" Megatron, Megatron worked "for" Sentinel (indirectly revealing that he actually wanted to taking over Decepticon through their bargains). He then took over full command of the Decepticons. Sentinel stayed out of most of the battle relying on the Decepticon warriors to carry out his plans, including Shockwave, Soundwave, Laserbeak, Barricade and Starscream (all of which would all be killed during the battle).

Transporting Cybertron and Death
Other Decepticons were placed around the world with a few of the Pillars. They were going to be used to open a Space Gate and bring Cybertron into the Earth's atmosphere. After the Red Pillar was deactivated by Optimus, (the Pillar that controls all the other pillars) Sentinel Prime fought all the Autobots and N.E.S.T. with little to no effort. While he was fighting the Autobots, Sentinel Prime told any surviving Decepticons and allies of the Decepticons to reactivate the Pillar. With the turning the fight, Sentinel attempted to escape, but Optimus intercepted him and attacked him. Sentinel managed to overpower Optimus and amputate one of his arms, and then prepared to kill him. At the same time, Carly (Sam Witwicky's new girlfriend) tried to convince Megatron to kill Sentinel Prime. She said that if Sentinel did succeed in killing Optimus and transported Cybertron, Megatron would be nothing more than Sentinel's new minion (and indirectly revealing Sentinel's true intentions). Convinced, Megatron rushed in, attacked Sentinel, and severely wounded him, claiming that Earth was his planet to rule. After the space bridge was destroyed, Optimus Prime fought and killed Megatron after refusing his insincere offer of a truce (knowing his true intentions and possibly done so as punishment of his previous actions). With his plans in ruins, the badly maimed and severely weakened Sentinel finally abandoned his pride; he begged Optimus for mercy and attempted to justify his actions, claiming all he ever wanted was their race's survival. But Optimus ignored him and, claiming that Sentinel had "betrayed himself", executed the treacherous Prime with Megatron's fusion shotgun. With Sentinel's death, the deaths of Ironhide and the human soldiers were avenged.

Age of Extinction
Despite being killed in the previous film, KSI manages to recover parts of Sentinel's body, particularly his head, which are used to create many man-made Transformers, including Galvatron, who is later revealed to be possessed by the still living mind of Megatron.

In spite of his death, he, Dylan Gould, and the Decepticon's actions are what causes the chance for humanity and Autobot's chance to reconcile over disaster that they caused became slim to none aside the presumably huge damage on the already dying Cybertron. This was proven where Cemetery Wind, which formed to dispatching surviving Decepticons began to targeting the unwilling Autobots until only six of them left (namely Hound, Bumblebee, Optimus Prime, Drift, Crosshairs, and Brains). Sentinel was indirectly responsible for the death of James Savoy's sister, driving him insane as a commander of Cemetery Wind. His crime records in Chicago also supporting Attinger's agenda to convince humanity to wipe out Cybertronian survivors on Earth (except Lockdown whom he made a deal with) and manipulated Joshua Joyce and KSI as his pawns to do so by creating an army of artificial transformers. Fortunately, all of their plans stopped by the reluctant Autobot survivors alongside freed Dinobots and their human allies (particularly Joshua that redeemed himself near the climax and supporting the Autobots and their human allies against Galvatron, Cemetery Wind, and rogue KSI drones).

Transformers: The Last Knight
Even though Sentinel Prime will never get to see it, his dream of Cybertron being restored was granted by Quintessa as she was able to use her technology to build it into a condition where Transformers may inhabit it once again.

Death
Killed by During the final battle Sentinel engages Optimus on a bridge away from the main battle but gains the upper hand by severing his right arm, and severely damaging his left. Before Sentinel can deliver the death blow Megatron shoots him from behind and angrily beats him down for stealing command back from him. While Sentinel lies wounded Optimus kills Megatron but as Sentinel tries to justify his actions and beg for mercy, Optimus refuses and shoots Sentinel in the chest then in the head.
 * Megatron (Caused)
 * Optimus Prime

Killed Victims

 * Ironhide
 * Skids
 * Mudflap
 * Que (Caused) 
 * Numerous counts of unnamed Decepticons and humans (Caused) 

Personality
Sentinel Prime at first seemed to be a heroic figure and a symbol of freedom to Optimus Prime, but later on it turns out that he is a corrupt psychopath who wishes to be dictator of everyone else, Cybertronian or human. As an Autobot, Sentinel had taught the value of freedom being everyone's right back to Optimus when the latter was the former's student. However, over the years Sentinel Prime has come to prefer having power and authority much more than enforcing freedom for everyone. Optimus claims that Earth should be the new home for their race as the humans welcomed them, although Sentinel being discriminatory despised the idea of sharing a planet with weaker, smaller organic beings when he could enslave them and he wanted Cybertron restored instead. Sentinel also proved to be greedy for power, as he forced Megatron to abdicate from being leader of the Decepticons and felt humans had no right to object to being used as his slaves.

Trivia

 * He is the second incarnation of Sentinel Prime to be in a negative light with Sentinel Prime from Transformers Animated being the first, albeit this Sentinel is far darker than his Transformers Animated counterpart.
 * Sentinel Prime is voiced by Mr. Spock himself: the late Leonard Nimoy, who also did the voice of Galvatron, in The Transformers: The Movie. Sentinel Prime even spoke, "The needs of the many outweigh the needs of the few", which was spoken by Leonard Nimoy's character Spock from Star Trek.
 * It is said that his face was meant to physically resemble famous actor Sean Connery.
 * Sentinel Prime was originally meant to appear in an original draft of the first film via hologram in the Allspark Cube after Sam Witwicky fell off the building after being attacked by Megatron, telling him about Optimus & Megatron's relationship.
 * Sentinel Prime is however mentioned by Sam Witwicky in the second film.
 * He was originally going to be named "Ultra Magnus", a failed Prime from the original Transformers movie and a protagonist in third season on the television show.
 * Sentinel Prime is colored yellowish-orange in the trailer of Dark of the Moon similar to a design of his in G1, though he is actually colored red throughout the movie.
 * In an original draft of Dark of the Moon after Sentinel Prime kills Ironhide, had featured him trying to kill Bumblebee but instead kills Skids who got in the way & then Mudflap after he tried to avenge his twin brother. It was cut due to negative views about the said Autobots. This is still seen in the comic book & novel adaptations (See gallery above).
 * Though he is portrayed as a villain, Sentinel Prime's film appearance & alt mode has been used to many outside incarnations of his on the Transformers universe such as Kre-O version & Angry Birds version.
 * At first, Sentinel was the key character in Transformers Dark of the Moon, though his betrayal towards the Autobots, and even Megatron as well, promoted Sentinel to be the true main antagonist for the rest of the film.