So to help everyone out, here's a production video detailing the new characters and the actors that play them - with a few clips from episodes we have yet to see. In it we have the Queen of Thorns, Olenna Redwyne (Diana Rigg), Missandei (Nathalie Emmanuel), Mance Ryder (Ciaran Hinds), Tormund Giantsbane (Kristofer Hivju), Orell (Mackenzie Crook), Jojen Reed (Thomas Brodie Sangster), Meera Reed (Ellie Kendrick), Blackfish Tully (Clive Russell), Edmure Tully (Tobias Menzies, recently seen in the last episode of Charlie Brooker's Black Mirror), Thoros of Myr (Paul Kaye) and Beric Dondarrion (Richard Dormer).
The scene near the beginning, between Tywin Lannister and Olenna, is not from the books, so a new plotline may be being developed there.
Read our review of the latest episode of Game of Thrones here.