Christopher Eccleston has revealed how becoming a bad elf for Thor: The Dark World meant learning a new language and transforming into a "reptile-weapon hybrid".
The former Doctor Who plays evil creature Malekith in the Thor sequel and talked about the process he had been through to become his character.
He said of Malekith's look, which took six hours in make-up each day: "We think it's a beautiful face in a sense. It made me think of reptiles which was a good clue to how to play him - reptilian, quite slow, methodical.
"We thought about Nosferatu, the imagery from that film... I felt like a combination between a reptile and a weapon."
Christopher, 49, also had to learn a new language for the action adventure, which was developed by a friend of director Alan Taylor's.
He said: "A colleague of Alan's, a linguistics expert who had worked with him on Game Of Thrones, created the thing and sent it to us and he sent it in a literal translation, which is incomprehensible, and then there was a phonetic translation which is a guide to how to say it.
"But we also had to adapt it to our voices, we had to decide on a music for it. It's inspired by the Finnish language so we listened to a lot of that."
Christopher admitted the end result of his elf transformation had left a lasting impression on him.
"It's really interesting to see yourself on screen so physically transformed and vocally transformed like that. It really is, and we hope it convinces people that these are an alternative race to the Guardians."
Thor: The Dark World, which also stars Chris Hemsworth and Natalie Portman, is in cinemas now.