10. The Master dies in The Doctor’s arms (The Last of the Time Lords)
As the Master lies dying from a gunshot wound, David Tennant’s Tenth Doctor is faced with not only losing a Time Lord who was once his friend, but the only one of his kind left. With Tennant at his teary best, the Doctor desperately begs him to regenerate, only for his nemesis to claim one last victory (until the next time, of course). By the time This Is Gallifrey starts to chime in and the Doctor lets out an anguished scream, the heart strings are very much pulled.