Ross Mullan

Ross Mullan is a Canadian-British actor and puppeteer, known for portraying White Walkers on the HBO television series Game of Thrones in its second to fourth seasons. He has appeared in episodes of Doctor Who and in the 2010 film Clash of the Titans.

WIKIPEDIA

GAME OF THRONES · S2, E10

Valar Morghulis

Season 2 Finale. Tyrion awakens to a changed situation. King Joffrey doles out rewards to his subjects. As Theon stirs his men to action, Luwin offers some final advice. Brienne silences Jaime; Arya receives a gift from Jaqen; Dany goes to a strange place; Jon proves himself to Qhorin.
GAME OF THRONES · S4, E4

Oathkeeper

Dany balances justice and mercy. Jaime tasks Brienne with his honor. Jon secures volunteers while Bran, Jojen, Meera and Hodor stumble on shelter.
GAME OF THRONES · S3, E8

Second Sons

King's Landing hosts a wedding, and Tyrion and Sansa spend the night together. Dany meets the Titan's Bastard. Davos demands proof from Melisandre. Sam and Gilly meet an older gentleman.
DOCTOR WHO · S8, E5

Time Heist

The Doctor turns bank robber when he is given a task he cannot refuse: steal from the most dangerous bank in the cosmos.