Natalia Tena who plays the "ugly" and weird Osha gets full on naked in the Game of Thrones Season 2 episode 6 (episode 16).
Osha plays the character who tried to kidnap Bran, Robb Stark's brother but failed and was captured and turned into a servant. She's since been loyal to the Stark family and even Bran himself.
Judging by her IMDB page, Natalia Tena is not too shabby in real life despite her weird character on the Game of Thrones. She's 26 and from London. She's also starred in the movie Harry Potter and the Deathly Hallows, Part 1 & Part 2
Here are some funny nude photos of her in the Game of Thrones: