Tom Hopper had big roles before Game of Thrones - he played Percival, one of the knights of the round table, in Merlin for three seasons, and he was pirate Billy Bones in four seasons of Black Sails - but nothing has had quite the same impact as his fleeting turn as Dickon Tarly.
We first met the character in season six, when Samwell Tarly (John Bradley) visited his father Randyll (JamesFaulkner) at the family home. But he wasn't named then, and he wasn't played by Hopper.
"A friend of mine, Freddie Stroma, played him," Hopper says. But when it came time to shoot season seven, Stroma had landed a part in another show and couldn't do it, while Hopper had just wrapped on Black Sails. They shared an agent, who suggested Hopper might step in.
"When I got the role I emailed Freddie to let him know," Hopper says. "It was a bit like telling your mate you were going to start seeing his ex-girlfriend. But he was really cool about it."
Dickon was the butt of a running joke (mostly on account of his name, but also for being a privileged "fancy lad", as Bronn put it). But Hopper was such a hit that he spawned internet memes, fawning articles, and even a fan page dedicated to his arms.
"It was a bit of a crazy whirlwind when those episodes came out," says Hopper, who is in Australia for the fan fest ComicCon. "It was great to be part of something like that. It's such a bonkers machine, that show."
At 196cm, Hopper is a big guy, with the sort of abs only a fierce devotion to the gym can maintain. And he concedes he's been a little typecast, as the big bloke in period action drama.
"When you do your first role you effectively brand yourself with images that have you in that costume. So when I first did Merlin, I started this trend of being sleeveless in armour, and it seemed to be this thing I did over and over again."
At least Game of Thrones bucked that trend. "This time, the armour covered my arms."
Hopper is about to shift gear again - he's just finished filming a comedy, I Feel Pretty, opposite Amy Schumer as a woman who falls off her spin cycle and suffers a brain injury that makes her believe she is a stunner.
"It's about how if you are super-confident, if you feel beautiful, you will appear beautiful to everyone," he says.
Hopper had never done comedy before, and it was not without its challenges. "My role is not really the funny man, but with Amy you have to have a certain comic ability because she's throwing curve balls at you left, right and centre, and you have to go with the flow," he says. "I'm doing an American accent in it as well, so having to improvise in that accent was a whole other skill I had to learn on the job."
At least he got to wear something other than a suit of armour.
"It was bizarre," he says. "I got to my trailer to put my costume on and there's jeans and a T-shirt, and I'm like, 'Right, is that it? Where's the rest of it?' I'm so used to pulling on all this other clobber."
As for GoT, Hopper has no inside knowledge but he does have his fingers crossed for the ending.
"I'd like to see Sam Tarly on the throne personally, because I love John so much," he says.
"I have a theory that it's him who's been narrating it the whole time, that it's actually his story; he had access to all the info at the Citadel. I've had a few discussions with massive Thrones buffs and they've backed it up."
So that's your hot tip: Game of Thrones will end with Samwell Tarly on the Iron Throne?
"Yeah," he says. "Why not?"
OzComicCon is i Brisbane September 23-24 and Sydney September 30 to October 1. Details: ozcomicon.com