[Potential Rogue One: A Star Wars Story SPOILERS ahead.]
Godzilla (2014) director Gareth Edwards' Rogue One: A Star Wars Story is the first of multiple planned "Anthology" or "Standalone" Star Wars movies that Walt Disney Pictures and Lucasfilm intends to release, in between the central installments or "Episodes" of the new Star Wars film trilogy (starting with director J.J. Abrams' Star Wars: The Force Awakens in December 2015). The Rogue One cast is quite impressive, with people like the Oscar-nominee Felicity Jones, Oscar-winner Forest Whitaker, and Hannibal fan-favorite Mads Mikkelsen amongst its ranks.
Mikkelsen has thus far kept quiet about who, exactly, he's playing in Edwards' Star Wars movie, though it appears he has now let slip what that character's name is. However, this revelation has now in turn prompted speculation: is Mikkelsen playing someone who is working against the Galactic Empire - as the actor has indicated is the case - or is he someone with ties to Darth Vader and the Imperial Forces, after all?
Although Mikkelsen has played non-villainous characters before, his rise in popularity over the past decade has certainly been largely tied to his "bad guy" roles - be they Le Chiffre in Casino Royale, Rochefort in The Three Musketeers (2011), or Dr. Hannibal Lecter on the Hannibal TV show. Mikkelsen is rumored to be circling another baddie role for Marvel Studios' Doctor Strange, though back at the 2015 D23 Expo the actor said (via StarWars7News) his Rogue One character will be something else:
"[My 'Rogue One' role] is a very important role, as much I can say. [My] character is actually not a bad guy, and then I can not say more."
More recently, Mikkelsen signed a poster for a RebelForceRadio user where he wrote the name "Galen" under his own signature, much like Zachariah Jensen wrote "Kit Fisto" - the Jedi character he played in Star Wars: Episode II - Attack of the Clones - under his own signature on the poster. The implication is that Galen is, in turn, the name of Mikkelsen's character in the Star Wars universe (and in Rogue One, to be exact).
PIC: Actor Mads Mikkelsen revealed the name of his ROGUE ONE character in this signature to RFR listener J.J. Good. Does GALEN ring any bells?
As noted by StarWars7News, the most famous Galen from the now-defunct (read: no longer part of the official canon) Stars Wars Expanded Universe mythology is Galen Marek (codenamed "Starkiller"), an extremely powerful Force-using Sith apprentice of Darth Vader; he serves as the protagonist in the 2008 video game titled The Force Unleashed. Such a character may not seem to fit with Mikkelsen's claims that he's "not a bad guy" in Rogue One (at passing glance, that is), but it's worth noting that in Force Unleashed there is a specific ending to the game where Marek ends up helping the leaders of the Rebel Alliance in their battle against Emperor Palpatine's Empire.
Furthermore, it's heavily rumored that Vader will make an appearance in Rogue One, so it stands to reason that one of the film's cast members will play one of Vader's secret agents who (when the story begins) is assisting the Sith Lord in his efforts to track down any/all of the Rebellion's spies and their own undercover agents. Or, rather, they appear to be doing that, anyway...
Upcoming Star Wars movies, TV shows, and books are free to draw inspiration from the old EU - hence the inclusion of EU superweapon technology in The Force Awakens - so it's certainly possible that some elements of the Galen Marek character (like, his first name) have been included in the "Galen" whom Mikkelsen is playing. Edwards has said before that Rogue One, which tells the tale of the Rebel mission to steal the original Death Star's plans, will be more of a grounded war story in the Star Wars universe - with few (if any) Force-users. Hence, whichever side "Galen" is on for most of the movie, he probably won't be skilled in the art of the Dark Side like Galen Marek is.
A story thread where Mikkelsen's character works for the Galactic Empire (maybe even Darth Vader personally), only to turn about and help the Rebel Alliance could provide "Galen" with a compelling arc in the larger Rogue One narrative, as scripted by Chris Weitz (Cinderella (2015)). It's not at all given that Mikkelsen is playing a character who bears any similarities to Galen Marek (not yet, anyway), and there are other issues - such as the age difference between Mikkelsen and Galen Marek - that do seem to point away from the former's character being influenced by the latter.
Nonetheless, as far as speculation concerning the unknown elements of Rogue One goes, it's not a bad theory, all things considered - agreed?
Star Wars: Episode VII – The Force Awakens hits theaters on December 18th, 2015, followed by Rogue One: A Star Wars Story on December 16th, 2016, Star Wars: Episode VIII on May 26th, 2017, and the Han Solo Star Wars Anthology film on May 25th, 2018. Star Wars: Episode IX is expected to reach theaters in 2019, followed by the third Star Wars Anthology film in 2020.