10 Most Heartbreaking Doctor Who Moments

The Tenth Doctor has been haunted by a prophecy that he will die when someone knocks four times. After saving the world in a tense, and supposedly his final battle, the Doctor discovers himself alive, much to his surprise.

His relief is shattered when he hears a knocking sound. He turns to see Donna's granddad Wilfred, trapped in a containment unit about to be flooded with radiation. Selflessly, Wilf tells the Doctor to leave him, but he cannot bring himself to do that, telling Wilf that it's his honour to take his place. They swap over, and the Doctor is hit by devastating radiation as Wilfred watches on helplessly. The Doctor realises his regeneration has started, leading to a farewell tour of his companions.

The Doctor visits everyone who's lives he has touched. We see where our favourite companions are now, and finally he sees Rose before she's met him, and tells her she would have a great year.

An Ood appears to sing to him, giving him the strength to fight through the pain. He walks into the TARDIS, where he says the now iconic, "I dont want to go." He regenerates, shooting energy all about the TARDIS control room, destroying his surroundings before morphing into Matt Smith.