Kristian Nairn in September 2024.Getty Images

Hold the door.

“Game of Thrones” star Kristian Nairn, best known as the sweet and simple Hodor, spills behind-the-scenes secrets in his new book, “Beyond the Throne: Epic Journeys, Enduring Friendships, Surprising Tales.”

“With me being a DJ as well [as an actor], my manager and I would always tour together, and over dinner and travel, we would talk about the past,” Nairn, 48, told The Post.

“And every time I’d come up with an anecdote from my past, he’d be like, ‘You have to write this down, you need to tell people this story!’ At first, I was a bit reticent. But as I did it, I found it was beneficial … [The book] became almost like therapy. I really enjoyed it.”

Nairn at the “Game of Thrones” Mother of All Auctions on Sept. 16, 2024.Getty Images

The memoir covers Nairn’s childhood in Northern Ireland, where he describes feeling like a misfit as a 6-foot-8 gay kid pressured to play rugby in school when he was more interested in being a DJ and a drag queen. The book also covers behind-the-scenes details about his time playing the mentally disabled Hodor on “Game of Thrones,” the gentle giant who traveled with Bran Stark (Isaac Hempstead Wright) and only ever said his own name.

Nairn said he did get some writing advice from George R.R. Martin, who wrote the “A Song of Ice and Fire” series of novels on which “Game of Thrones” is based.

“I [saw] him only about three weeks ago, George is a friend of mine, I love him to pieces,” he said.

“The first time sitting down with him, author to author, we talked about deadlines. And he made the very funny quip where I was talking about deadlines being stressful. He said, ‘I’m 12 years late, Kristian. I understand about deadlines.’”

Nairn in “Game of Thrones.”

In the book, Nairn, who was an acting rookie on “Game of Thrones,” also opens up about feeling uncomfortable doing a nude scene on the show. For a scene when Hodor does full-frontal nudity, Nairn was fitted with a prosthetic appendage.

As Nairn details in the book, when the props department gave him that prosthetic, he saw his co-star, Richard Madden (who played Robb Stark), swinging it around in the parking lot, exclaiming, “Look at the size of this!”

Nairn said he didn’t give Madden a heads-up about mentioning that in the book.

“Well, I think if you’ve got the balls to run around a [parking lot] with a prosthetic penis, you have to realize that it’s going to appear in print at some stage,” he said.

“I haven’t told him [that’s in the book], no. But I’m sure he won’t be shocked.”

Nairn at the “Game of Thrones” Season 6 premiere in 2016.Paul Smith/startraksphoto.com

Isaac Hempstead Wright (left) as Bran Stark and Nairn as Hodor in “Game of Thrones.”HBO

In his memoir, Nairn, who was also in Max’s pirate show “Our Flag Means Death,” described having anxiety about doing the nude scene and how he felt that his misgivings were ignored on set.

“I think it’s an industry-wide thing, not just ‘Game of Thrones,’” he said.

“We do have intimacy coordinators now. I don’t think they were around back then. I know they’re popular and common on sets now. They make sure you’re feeling OK and everything is by the book. So, hopefully that has made it better.”

He added that he doesn’t only feel bad about that, explaining that getting through the day of filming “did become a point of — not victory for me, but almost victory over myself. Because I really didn’t want to do it, and I managed to look for the silver lining. I saw it as being valuable to represent people who aren’t the Hollywood trope.”

Nairn as Hodor in “Game of Thrones.”

He said he didn’t give any other co-stars a heads-up about mentioning them in the book, but he’s not worried about their reactions.

“I was never going to make up any nonsense about people. It’s a nice group of people, and it felt like a big weird dysfunctional family,” he said. “Isaac is probably the one where I can imagine we’ll still be in touch at the end of my life. I can’t imagine not being friends.”

Nairn did say, however, that some of his co-stars said to him about his book, “I hope you were nice about me!’”

But, he added: “There’s nothing to worry about. Everyone has, I believe, a fair depiction. It’s like handing in your homework for the teacher, I want to hear what they think [about the book], I can’t wait to hear.”