He's renowned as a meticulous method actor who painstakingly prepares by creating detailed biographies of the characters he plays.
But no amount of homework or training could prepare Richard Armitage to play Thorin Oakenshield, the leader of the Company of Dwarves, in The Hobbit trilogy.
Armitage had his fair share of action in previous roles in television's Spooks and Robin Hood and a brief turn as a Nazi spy in the first Captain America movie.
But he admits he was overwhelmed by the physical intensity of playing the pivotal part in Peter Jackson's epic franchise.
"it was quite a shock when we first started. i remember doing the sequence in the goblin tunnels from movie one and it was so hot and so taxing that a lot of the dwarves and the stunt guys were coming off the set and vomiting. that's how extreme it was," he reveals. "that's why, from the start, i viewed these films as a marathon rather than a sprint.
"it's just as well i did, because that's how they turned out.
"On the last day of filming, i honestly thought i was going to be carried out on a stretcher because i was on my knees from exhaustion. it was also incredibly moving filming those last scenes, because it marked the end of a very long, emotional journey."
Armitage says he became so absorbed in his role as Thorin Oakenshield that he even ended up dreaming in character.
"I started having weird dreams and realising it's not me, it's the character. I used to have this recurring dream about going into a tunnel and not being able to find my way out. it was something to do about the scenes with the secret door.
"But it's kind of cool because you don't have to work that hard if your mind is already wandering in that place, without you having to remind yourself to think about the character; it's just there in your subconscious ... that's what you want: you want to lose yourself in the character."
"i think it's an anxiety dream and it mirrors the anxiety that thorin feels about taking his people back to the mountain. the magnet is the gold but the repellent is the dragon. so he has this terrible dilemma of wanting to find what's in there, but what's in there could be a ticking bomb that destroys his people too."
Despite the pressures of the shoot, Armitage insists he never held any reservations about accepting the part, nor having to relocate to New Zealand during filming. in fact, he relished it. "I remember when i first sat down with Peter Jackson, during casting, and he said: 'the thing is, we're going to shoot this in New Zealand and it's going to be a long commitment', expecting me to question it, or somehow be disappointed by that," he recalls. "But that was possibly the biggest pull of all.
"Part of the adventure, for me, was the chance to go to New Zealand and immerse myself in Middle-earth, which many fans - and Kiwis - believe New Zealand to be. I wanted to experience that whole mythology and feel what they did when they shot Lord of the Rings there."
He admits he wasn't disappointed by what he found. in fact, his expectations were dwarfed by the realities of his experiences while filming.
"They'd be days we'd go to work and there'd be a line of helicopters that would take us to the top of a part of the mountain, because there were no roads up there. Then they'd leave and we'd be all alone, filming in a place where very few people had ever stood. It was magical."
And he was able to combine work with recreation - or that is how it might look in Desolation of Smaug's escape-by-barrel scene, which offered Armitage and his cast a spot of whitewater rafting. Though the weather cut that part of the shoot short.
"When we were shooting the barrel scene on the Pelorus river, we were supposed to have one more day of shooting and a huge storm was coming in so they pulled the shoot and we flew back to Wellington. But the big storm came in and washed the road away between where we were shooting and the location, so if we'd gone to the location we'd all have been stranded in the location. and it took six to seven weeks to rebuild that road, which made me realise how fragile the infrastructure is there, in New Zealand. But I kind of like the fact that it's like that, that it's not too intrusive."
Armitage says despite the wild ride of part two, which presumably ends with team dwarf encountering the fiery beast of the title, it's what Thorin faces in next year's part three that worried him the most.
"The thing that was always looming for me - and I don't think this is giving too much away, maybe it is - was the Battle of the Five Armies, because it contains so much for my character. In terms of physical effort we were always working towards that battle [scene] because the battle had to be bigger and better, physically, than anything before.
"So that scene was always something that I was frightened of. But I was also using that with the character because, for me, it represented the beast - the dragon.
"So as Thorin is on his journey into the mountain it had that same kind of anxiety of 'I know what it's going to take to combat this and i don't think I have it'.
"So it was kind of useful to have that fear inside me."
And when he wasn't acting his little dwarf king legs off, the actually rather tall Armitage was off having a very good time.
"I visited a lot of remote, ruggedly beautiful and pristine places that I still dream about, even now. I also did a lot of fly-fishing, kayaking and skied just about every mountain there was - not that I told peter [Jackson], at the time. The whole experience has definitely made me want to retire to New Zealand.
"Being there, filming The Hobbit, has totally changed me."
For American actor Lee Pace, playing Thranduil, king of the woodland elves in The Hobbit meant he was playing the father to Orlando bloom's Legolas, the elf hero of the Lord of the Rings film trilogy.
In Middle-earth years, Thranduil is centuries older than his son. In the real world, the 34 year-old Pace is two years younger than Bloom.
"I love Orlando. We had a great time on set," he says of his film offspring but older colleague. "I learned a lot from him, to be honest - just understanding what the concept is with these creatures."
Thranduil isn't much like the other Tolkien elves we've met before on screen. He's not like the serene pointy-earred folk of Rivendell, like Elrond or Galadriel. This Elvenking comes with a crown of ornate twigs matched by a chip on his shoulder.
"There's a perfection to them, but they live forever, so is that perfection or a curse?" wonders Pace. "He's thought and killed a lot; he's taken life a lot and survived a lot of battles and he's sad, he's hurt because in a buddhist way he's not immune to the suffering, and it changes who he is.
"He's not a happy elf, not a nice elf."
He's also the sworn enemy of dwarf leader Thorin Oakenshield (Richard Armitage) whose wee gang he takes captive during the part of the Hobbit story covered by The Desolation of Smaug.
"The first scene that I shot was with Richard - and talk about being thrown right in at the deep end. It's a pivotal scene for both of the characters and it's the first scene that I shot, the confrontation between the king of the elves and the king of the dwarfs and they do not see eye-to-eye.
"That's one of the interesting things about The Hobbit - the conflict between the elves and the dwarfs - and we really worked hard to make that conflict specific.
"When Thorin comes through again and i catch him trying to disturb a sleeping dragon I'm determined to stop him ... [Thranduil] doesn't want to be his friend, he just wants people to kneel in front of him."
Pace seems to have a thing for immortality. before donning the ears and blonde wig to play Thranduil, he was best known for the short-lived fantasy-comedy television series Pushing Daisies - in which his character Ned had the ability to revive the dead.
As well, he was "good" vampire Garrett in the final film of the the Twilight Saga.
Jackson cast him in the hobbit trilogy after seeing him in adventure fantasy film The Fall.
For pace, the shift to New Zealand to the shoot fulfilled more than one ambition.
"All I ever remember wanting to do, as a kid, was act - nothing else. in fact, about the only thing, other than acting, that I'd like to do is go live in the woods, build a log cabin at the top of a hill and try and hide away from the modern world."
"So, in many ways, the Hobbit ticked all the boxes: not only is it the ultimate acting challenge but it's also biggest adventure you could go on while making a film."
The role offered a mix of mental and physical demands.
"The scenes in Elvish were incredibly difficult because we had to learn a completely new language - I'd hate to see the out-takes from those scenes," he laughs.
"Also, the fighting was a huge challenge because you're on set with 200 stunt guys swinging these huge pieces of metal around and trying not to hurt anyone, or get hurt yourself. It was pretty intense, at times. The fighting was one of my favourite things that i did in the movie, yeah, because he's tough. He's like a game-changer when he enters battle."
Pace says his year-and-a-half stay in New Zealand has also rekindled his love of the great outdoors, with most of his time off spent tramping or skiing.
"You know, i had a sense that going down to new zealand to do the hobbit would be one of those life-changing experiences and that's exactly what it's turned out to be," he adds, seriously. "Getting to work alongside all these incredible actors like Ian McKellen, James Nesbitt and Billy Connolly, who i adore, was an eye-opener.
"It made me appreciate how much I still have to learn as an actor. But I was there, like a sponge, soaking it all up."