In his recent Not A Blog post, GRRM confirms that we have guessed the right actress to play the role of Osha. She will be portrayed by Natalia Tena. The clues come together in exactly the way The_Rabbit’s solution suggested. Here is what George has to say about her:
Fantasy fans will know Tena best for her portrayal of the purple-haired Nymphadora Tonks in the Harry Potter films. When I saw that she was reading for Osha, my first thought was, “She’s great, but no way, she’s too young and too hot.” Then I saw her reading, and none of the other Oshas had a chance. Her charisma grabbed me by the throat and I could not take my eyes off her. David and Dan felt the same way. We’re all thrilled to have her.
He also presents three from the recent casting flood, Emun Elliot as Marillion, Peter Vaughan as Maester Aemon, and Margaret John as Old Nan. More is promised later, as GRRM is too busy writing ADwD to deal with all of the new roles and actors at once.
Hear Me Roar: Judging by what George has to say about Natalia Tena, hers is the mysterios role that got cast a bit differently from what the character is like in the books. We have a younger and more attractive Osha, and we guessed right once more. I do not mind her that way one bit – she does not clash with my mental idea of Osha, quite the contrary.