Grand Moff Tarkin

Warning:  Spoilers  may follow.

Grand Moff Wilhuff Tarkin, also known as Governor Tarkin, is a minor antagonist in Star Wars: Episode III - Revenge of The Sith, as he turns Anakin into Darth Vader. He later appears as a major antagonist in Star Wars: The Clone Wars and Star Wars: Rebels, and is also the true main antagonist of the 2016 film Rogue One: A Star Wars Story and its 1977 sequel, Star Wars: Episode IV - A New Hope.

He was portrayed by Wayne Pygram in Revenge of the Sith, and was voiced by Stephon Stanton in Star Wars: The Clone Wars and Star Wars: Rebels. He was also portrayed by Guy Henry in Rogue One, and Peter Cushing in A New Hope.

Star Wars: The Clone Wars
In this television series, the young version of Tarkin appears in the Republic Navy as a Captain and later an Admiral during the Clone Wars.[3]

In the third season, Captain Tarkin and Jedi Master Even Piell are ambushed and attacked by Count Dooku's Separatistforces. Prisoners to the Citadel, Tarkin and Piell are freed from captivity by a rescue team. Initially pessimistic about being in enemy territory, Tarkin puts himself at odds with Anakin Skywalker, but their respective opinions of each other improve when each realizes that they are mutual acquaintances of the Supreme Chancellor. During a skirmish, Tarkin fights with Osi Sobeck and attempts to execute him, but fails when the Citadel's sadistic caretaker swiftly retaliates and nearly kills Tarkin. However, Tarkin is rescued just in time by Ahsoka Tano.

In the fifth season, Admiral Tarkin appears resembling his original character. After the funeral for the Jedi Temple's bombing victims and the murder of Letta Turmond, Tarkin assumes that Ahsoka Tano is the culprit and attempts to have the Padawan arrested. Ahsoka flees into the sewers, but is eventually recaptured. After Ahsoka is expelled from the Jedi Order and tried before a jury of senators, Tarkin heads the prosecution while Padmé Amidala heads the defense. Despite Amidala's impressive defense, Tarkin casts doubt by mentioning that Tano had been seen with Asajj Ventress. After Tarkin and Amidala's arguments conclude and the jury reaches a verdict that the Supreme Chancellor is about to read, Anakin Skywalker arrives with the true mastermind of the crimes; Ahsoka's treacherous friend and fellow Padawan Barriss Offee.

Star Wars: Rebels
In this television series, Tarkin, now with the title of Grand Moff, visits the planet Lothal to deal with its growing insurgent activity.[4] He reprimands Minister Maketh Tua, Agent Kallus, and the Inquisitor for their repeated failures to stop the planet's rebel cell. Tarkin has the Inquisitor execute Commandant Aresko and Taskmaster Grint for their inability to deal with the cell's leader, Jedi Kanan Jarrus. Later, Tarkin sets a trap for the rebels and manages to capture Kanan during their mission to send a message through one of the planet's communication towers. The rebel's message gets sent out, but Tarkin then orders the tower to be destroyed.

Star Wars: Episode III - Revenge of the Sith
Tarkin oversees the Death Star I's construction after being told by Emperor Palpatine to do so off-screen, with Darth Vader watching with him.

Rogue One: A Star Wars Story
He appears as as the true main antagonist of the 2016 prequel (although having less screen-time than Orson), commanding the Death Star I, which Galen Erso had built for him. He at first tests his Death Star, and lets Orson Krennic choose the locations.

After watching the functions of the Death Star with Orson, he was impressed of his new weapon. He and Orson however get into a brief argument, as Tarkin says he will prove Orson wrong. As Orson wants the weapon for himself, without Tarkin guiding him, Tarkin informs him there is a traitor from Galen's facility, pointing out to Orson that he is failing, and ordering him to kill the traitor.

Orson goes to Galen Erso's research center. However, Galen revealed he had only built the Death Star so Tarkin or Orson wouldn't. Galen was killed during a battle in the research center. As Orson goes to his own research center on Scarif, Grand Moff Tarkin who is informed that Orson is on Scarif, sends Darth Vader and his fleet to deal with the rebels, and prepares to extract the research which Orson extracts, including Galen's hidden messages, just as expected.

He manipulates Orson into finding the hidden message of Galen's, as Orson does his job. Later, Tarkin realized he has to do things by himself, as he assumes that Orson had failed, as he expected. Therefore, he destroyed Jyn Erso, Cassian Andor and even Orson Krennic by shooting his weapon on Scarif and destroying it. Tarkin had later sent Darth Vader to get the tape with the message recorded on it, however, it was too late, as one of the Rebel soldiers have escaped and delivered it to Leia first.

Star Wars: Episode IV - A New Hope
Grand Moff Tarkin eventually becomes the Governor of the Imperial Outland Regions and commander of the Death Star I. After the Emperor dissolved the Galactic Senate, Tarkin and Darth Vader are charged with pursuing and destroying the Rebel Alliance. He then orders Darth Vader to bring Princess Leia to him, so he can either destroy Alderaan with a copy of the death star or destroy the base of the Rebels. His plans work, and he orders Leia to reveal the location of the Rebel Base. She reveals it is on Dantooine, however, he decides to destroy both of his targets, and he manages to destroy Alderaan first. He later occupies the Death Star I itself. In the film's climax, Tarkin refuses to evacuate, and orders everyone to continue the operation anyway. Thereafter, he is killed by Luke Skywalker, who destroys the Death Star with his spaceship, while Tarkin is still on board.

Trivia

 * In Rogue One and A New Hope, Tarkin is the true main antagonist because he had much bigger plans than anyone else, even Orson Krennic and Darth Vader.
 * This is proven even more so as Emperor Palpatine is not in those films.