The hardest part of filming polar exploration drama “The Terror” should have been the cold environment.

But, for Jared Harris, it was actually his co-stars.

“When I first met [Tobias Menzies and Ciarán Hinds, who both starred in ‘Rome’] I totally fanboyed over both of them, because ‘Rome’ is one of my favorite shows of all time,” says Harris, 56. “I just kept asking them questions about the show, and eventually they said, ‘Jared — we’re in rehearsal, let’s talk about this later.’ I just couldn’t help myself!”

Produced by Ridley Scott and airing on AMC (Mondays at 9 p.m.), “The Terror” is a story of endurance and man vs. nature set in the 1840s. Based on the bestselling 2007 novel of the same name (which is a fictional account of the real-life lost Franklin expedition), the 10-episode limited series follows crews on two of the British Royal Navy’s polar explorer ships on an ill-fated quest to seek the Northwest Passage. (One of the ships is called HMS Terror, hence the show’s name.)

When they become stuck in ice, all hell breaks loose — quite literally, since the story also has a horror element. As the crews fight to survive, it becomes apparent they’re being hunted by a mysterious creature.

Harris plays Francis Crozier, the pragmatic captain of HMS Terror.

“I like the confidence in that [the writers] didn’t feel like they had to have ‘jump’ scares,” says Harris. “It was really grounded, a very character-based story. A lot of the time, the scripts you get to read are remakes or reboots or sequels or prequels. This was a completely original story.”

Harris is no stranger to period dramas, having also starred in “Mad Men” (as Lane Price) and “The Crown” (as King George VI). As a self-professed history buff, he says he relished the chance to dive into research for “The Terror.”

“It’s one of the things I do enjoy about the job — going down the rabbit hole,” he says about “The Terror.” “It was so dangerous, polar exploring, and trying to find the Northwest Passage; they said there had been more successful trips to the moon.”

Surprisingly, the bitter cold (“The Terror” was shot in Budapest) wasn’t a hindrance to production — in fact, Harris says, it helped him get into character. “That helps put you into the environment, the mindset, to give you an inkling of what these people were facing.

“It actually was really cold when we started shooting; it was the dead of winter there. They were going to refrigerate the sound stages, and they saved themselves a lot of money, because it was cold enough [that] you could see our breath.”

Even though Harris enjoyed researching polar exploration and has starred in a wide range of historical dramas, he says there’s still one era missing from his extensive resume: ancient Greece, and particularly, Sparta.

“That period of history has always fascinated me — Greek history, Greek mythology,” he says. “I was just bitterly disappointed that I didn’t make it into [the 2006 film] ‘300’ — because by the way, back then, I had abs!”