Aidan Gillen's latest role was decades in the making.
The Irish actor -- known for his role as the ruthless Littlefinger on "Game of Thrones" and councilman Tommy Carcetti on "The Wire" -- is wrapping up the first season of the History series "Project Blue Book," named after the real-life investigation of UFO reports in the 1950s and '60s.
Gillen stars as famed ufologist J. Allen Hynek, a part that intrigued him after growing up a fan of "Close Encounters of the Third Kind" and Carl Sagan's "Cosmos."
"Those are probably what got me interested in just asking the questions of what's out there," Gillen, 50, told the Daily News. "Because you're surrounded by people, generally, who don't want to know about what's out there, or people who never leave their own town. ... I've never found it to be anything scary about what might be out there or the notion that there's other life forms in our universe. It seems natural to me."
Each episode is based on reports filed during the Air Force's real Project Blue Book probe, which ran from 1952 to 1969, and centers on Hynek's attempts to make sense of various phenomena.
The first season has been building up to the 10th and final episode -- set to air Tuesday at 10 p.m. ET -- in which a bizarre occurrence takes place in Washington, D.C., in 1952.
"The last (show of Season 1) kind of delivers one of the more sensational episodes, and is based on one of the more sensational reports," Gillen teases. "It's one of the most widely reported UFO sightings in a really public place, so it seemed like a good one to close on."
"Project Blue Book" has already been renewed for a second season, and Gillen says there's still "loads and loads of reports" to use for future episodes.
It's the first major American TV gig for Gillen since his "Game of Thrones" character met his demise during Season 7 in 2017.
He also recently played Queen's manager, John Reid, in the musical biopic "Bohemian Rhapsody," and is set to return for the fifth season of the British series "Peaky Blinders."
Gillen said it wasn't tough walking away from the wildly popular "Game of Thrones" or "The Wire."
"I don't find that hard at all," Gillen said. "I really enjoy walking away actually. ... I always like my last day playing a character."
"I'm kind of a don't-look-back man," he added. "I do think about this stuff, and some things are quite hard to escape. ... 'Game of Thrones,' of course. I talk to people on the street about that every day. (But) generally my thing is, walk away."
Gillen said his focus now is on "Project Blue Book" and Hynek, who died in 1986 -- adding his research of the astronomer's life showed him to be a "very interesting, unusual, thoughtful individual."
"The genre, the story and the character, there was quite a lot going for it," Gillen said. "Also, I'd been playing that character in 'Game of Thrones' for a number of years, and wanted to get someone a bit warmer and more likeable."
This article is written by Peter Sblendorio from New York Daily News and was legally licensed via the Tribune Content Agency through the NewsCred publisher network. Please direct all licensing questions to firstname.lastname@example.org.