Star Wars: Does Grand Moff Tarkin Know Darth Vader Is Anakin Skywalker?
Star Wars villain Darth Vader's (David Prowse) secret identity as protagonist Luke Skywalker's (Mark Hamill) father, Anakin, is one of the most iconic plot twists in film history. George Lucas, however, allegedly didn't intend for Luke's dad and Darth Vader to be the same person until a rewrite of the "Star Wars: Episode V –- The Empire Strikes Back" screenplay. The implications of this reveal have fueled countless canonical Star Wars projects, including the prequel film trilogy, the "Clone Wars" TV show, a lengthy comic book series, and plenty more.
One plot detail absent from any canonical film or TV series that has become a recurring subject of fan speculation is whether or not Grand Moff Tarkin (Peter Cushing) knows Vader's identity during their time working closely together for the Empire.
The clearest answer to this question arises in a novel called "Tarkin," published in 2014. At one point, Tarkin explicitly floats the idea to himself that Vader and Anakin Skywalker are the same person. Later, Emperor Palpatine probes him for this information, and Tarkin keeps it to himself, passing a test to determine whether he can keep this important secret.
Fans have floated some additional justification for Tarkin's knowledge of Vader's identity
The sole, unambiguous confirmation that Grand Moff Tarkin is effectively aware that Darth Vader is the same person as Anakin Skywalker takes place in the "Tarkin" novel. That said, fans in a Reddit thread about this question have proposed a couple of reasons this must be the case, using evidence directly from the primary film continuity.
For instance, the thread's top comment, by u/epicjeff, points to the fact that in "Star Wars: Episode IV — A New Hope," Vader calls Obi-Wan Kenobi (Alec Guinness) his former master. This blatantly evokes Vader's past life as Anakin, and Tarkin doesn't question it. Of course, if it's true that Lucas didn't know Vader was Luke's father when writing this scene, the reveal is an unintended consequence of the subsequent movie's big plot twist.
Meanwhile, u/ewokwarrior_ mentions that Anakin is in charge of the attack on the Jedi Temple after Palpatine executes Order 66. By this point, Anakin has taken on the Darth Vader mantle but has not yet lost the fight with Obi-Wan on Mustafar, so he isn't wearing his iconic suit. Tarkin, presumably, knows about the attack on the Jedi Temple and can figure out that its leader is the same person as the Darth Vader behind the black mask.