3. Iain Glen (Father Octavian/Jorah Mormont)
Iain Glen tends to lend gravitas to everything he does and he certainly did that in the Series 5 two-parter The Time of Angels/Flesh and Stone. The commanding officer of the military clerics tracking down a Weeping Angel, he knows a lot about River Song's (then mysterious) past and forces her to help them, but proves competent, courageous and honourable while they're fighting the deadly statues. He dies in front of the Doctor, caught by a Weeping Angel, but goes out with a lot of his dignity still intact. He's probably better known now for playing Ser Jorah Mormont, though, an exiled knight in the service of Daenerys Targaryen. Initially a spy, he helps Daenerys to adapt to the various places she finds herself in and becomes one of her most trusted advisors along the way. Over the course of their relationship Jorah appears to fall in love with the Khaleesi and becomes fiercely loyal, only to be exiled from her prescence when his former spying is discovered.