The fourth season of Game of Thrones is due to get underway in the Spring, with new additions to the cast including Yuriy Kolokolnikov (Intimate Parts) as Styr, Mark Gatiss (Sherlock) as Tycho Nestoris, Roger Ashton-Griffiths (Gangs of New York) as Mace Tyrell, Pedro Pascal (Graceland) as Oberyn Martell, Indira Varma (Rome) as Ellaria Sand, Struan Rodger (Doctor Who) as the Three-Eyed Raven, Michiel Huisman (Nashville) as Daario Naharis, Dean Charles-Chapman (The White Queen) as Tommen Baratheon, Icelandic strongman Hafþór Júlíus Björnsson as Gregor 'The Mountain' Clegane, Octavia Selena Alexandru (Ward 3) as the Child of the Forest and Joseph Gatt (Banshee) in an as-yet-unrevealed mystery role.