20 Amazing TV Plot Twists You Wish You Could Relive

Yes, 2007's Master-themed two-parter (the one where the Doctor became space Jesus) is terrible, but as for the twist that started it off? That's another story. 

In the series' 11th episode, Utopia, the Doctor and his companions Martha Jones (Freema Agyeman) and Captain Jack Harkness (John Barrowman) end up in the year 100 trillion. They try to help some of the last humans find a new home, including an amiable scientist named Professor Yana (Derek Jacobi). 

But then, Martha notices something strange in Yana's possession. A few episodes earlier, the Doctor had used a chameleon arch to become human and hide from some aliens that were pursuing him. This device resembled an old watch... and the professor has an identical watch in his possession. 

Once Yana examines the watch, some voices from within encourage him to open it, voices older fans would've instantly recognized... and once he does, he regains his true identity. He's the Master, a villainous Time Lord from Classic Who. Prior to this, the Doctor had believed he was the last of the Time Lords, and now everything was flipped on its head. 

It doesn't end there. In the next episode, a regenerated Master is revealed to be posing as Harold Saxon (John Simm), the Prime Minister of the UK who'd been name-dropped multiple times throughout the preceding series. Simply put, this is the best Doctor Who plot twist ever, and given how terrible the show has been lately, that's unlikely to change anytime soon.