“Jaqen H’ghar” (Tom Wlaschiha)
Who: One – possibly more (you just never know with these guys) – of the Faceless Men of the House of Black and White in Braavos, he has trained Arya Stark to be a lethal assassin, or “no one.”
Last seen: In the Hall of Faces in the House of Black and White, agreeing to allow Arya return to her family in Westeros.