Gillen wasn't looking to play the complete opposite of Littlefinger. But after seven years of scheming, it's an 'added bonus.'
The 50-year-old actor said goodbye to Westeros and hello to the unknown with History's Project Blue Book, a new series based on the real-life top-secret investigations into unexplained phenomena -- like UFOs -- conducted by the United States Air Force.
"So many people saw Game of Thrones and a character that's cold and manipulative," he told ET of his GoT role during a visit to the show's Vancouver set in March, calling the switch in characters an "added bonus." "It'd be nice to be known, hopefully, for not as a scheming evildoer."
Gillen's Project Blue Book character, Dr. J. Allen Hynek, is anything but scheming. In fact, he's on a mission to uncover the truth. The real Hynek was a family man, an astrophysicist and college professor before being recruited by the Air Force to spearhead inquiries into unidentified flying objects and the like. He was a skeptic, and the only civilian on the investigation, which lasted 17 years, from 1952 to 1969.
"When I read the first [script], I was intrigued. I thought, 'I could do that.' This guy obviously has to come across as really intelligent, but not a bore, and approachable and warm. Not only can I do that, but I haven't done it for a while. I've played warm characters, but not many recently," explained Gillen. The actor, who wasn't shooting scenes that day, came in solely for ET's interview, and if that didn't demonstrate his passion for Project Blue Book, the next 42 minutes did.
"He's a very interesting character," Gillen continued, pausing to inquire about our familiarity with the real Hynek and deciding to give a brief biography anyway. Among the highlights of Hynek's achievements was the establishment of the Center for UFO Studies, several published books and the influence he had on Steven Spielberg's sci-fi classic, Close Encounters of the Third Kind. "Hynek came up with that terminology," Gillen noted. "And if you look at the original long-form trailer for [the movie], which is 10 minutes long, he's in there."
Gillen was 11 years old when Close Encounters was released in 1977, and one of the first things he did when preparing to play Hynek was pop in the Blu-ray for another viewing. "It had had such an impact on me as a kid... Hynek himself appears in Close Encounters, it's a cameo, but Spielberg thought fit to put him in there," Gillen trailed off, appearing to play through his childhood memories in his head, before turning his attention back to the show. "So, yeah, [the show is] a 10-part drama focusing around Project Blue Book, around Allen Hynek, and this character, Captain Michael Quinn, who's a straight up Air Force type guy, but they play well off each other, you know?"
Michael Malarkey plays Quinn, whose creation is an amalgam of others who worked on the real Project Blue Book. Those in the Hynek family are the only characters who keep their names, but Gillen wasn't concerned with the pressure of getting his character right.
"I've played real people before," he noted. Most recently, Gillen starred as music manager John Reid in the Queen biopic, Bohemian Rhapsody. "And I've been in touch with [Hynek's sons], Joel and Paul Hynek. To have that as a source is huge... They understand that every episode is television drama, but it's based on history."
Even on his day off, the wheels are turning for Gillen, who couldn't seem to stop thinking about Hynek. It's that particular obsessiveness and genuine interest that Project Blue Book creator David O'Leary first recognized in the actor's performance as Littlefinger. O'Leary believed it would translate well into a portrayal of Hynek.
"I do immerse myself in whatever character I'm playing," Gillen confirmed. "Game of Thrones and Project Blue Book, they're different worlds... but to immerse yourself in the period's detail, though, is really helpful, and we have a really good look for this. They've pulled the stops out in terms of design, and we've got a great cinematography team and production design and costume design. So, when you put your costume on and get in there and get in the world of the script, it's quite easy just to slide in."
Being a believer in Hynek's work also helps. "I think it's extremely unlikely that we, on our planet, are the only intelligent life in the universe. I think that's bordering on ridiculous thinking," Gillen expressed.
He also believes in roles that are spectacular or out of the ordinary. "I don't mind being in a series that lasts, if it's good and if the role's good," Gillen answered, when asked if he found it daunting to take on a show with 17 years worth of material, following a decade's run on Game of Thrones. "I can't think of anything worse than -- and I wouldn't do it -- signing up for something that I thought wasn't going to be good, and the thought of being in it for seven years... at this stage of my life, I don't need that, you know?"
But if potential Project Blue Book viewers are still unconvinced, Gillen's reaction is unwavering, asserting that the audience will probably be on board after the first episode.
"I don't really want viewers to know anything before they tune in. It's being made by people who take the subject matter and the genre seriously, and want to bring them on a trip that is fantastical in a way that is rooted in actual fact and history," he shared. "I think it's going to be thoughtful and fun. I'm not sure which order. There will be some flying saucers..."
Project Blue Book premieres Tuesday, Jan. 8 at 10 p.m. ET/PT on History.