Since its relaunch in 2005, Doctor Who has become a global phenomenon. Of course, a lot of its success is due to the charisma and energy of the Doctor themselves, and their companions at the time. However, the variety of exciting and absolutely shocking storylines are also partly responsible for the show's success.
The series has always thrived on an excellent cliffhanger, but on occasion, there are moments within the sci-fi drama that completely stun even long-time fans. Whether it's the surprise return of an old character, or a line that changes the entire history of the show itself, Doctor Who is no stranger to plot twists.
Doctor Who's first season-long arc was one of its best. Throughout Season 1, the Doctor and Rose Tyler were haunted during their travels through time and space by two words: Bad Wolf. This mysterious phrase had no meaning and seriously worried the Doctor.
In the two part season finale, the Doctor and Rose were forced to face Bad Wolf and what it might mean. It transpired that Rose sent the words as a message to herself in an effort to save the Doctor, after she had looked into the heart of the TARDIS.
The Season 2 finale of Doctor Who was incredibly dramatic. It featured the Torchwood Institute for the first time, an army of ghosts, and said goodbye to one of the Doctor's most beloved companions. Despite all that, there was more to come.
Thanks to various trailers, viewers knew that the Cybermen were returning for the finale, but one things that was kept secret was the return of the Daleks, hidden away in an impossible Sphere. This twist singlehandedly started the war between the Cybermen and the Daleks.
The real identity of River Song was possibly one of Doctor Who's longest ever mysteries, with the answer only being revealed 3 years after River made her debut. During that time, there were so many fan theories about who River really was.
Fans finally got the answer that they had been craving in the Season 6 midseason finale, "A Good Man Goes To War", where it was revealed that River Song was actually Melody Pond, the daughter of Amy and Rory.
Back in 2013, speculation was at fever pitch. Doctor Who's 50th anniversary episode was due to be aired on the 23rd November and fans were desperate for any pieces of information concerning the special. One such piece was that John Hurt had been cast for an undisclosed role.
No one knew who Hurt was going to play, only that it must be a significant part for such a renowned actor. Surprisingly, his character was revealed in the final moments of the Season 7 finale in a scene that completely blew everyone away.
Almost since the beginning of Season 4, the Tenth Doctor's upcoming demise was hinted at. However, it didn't start to become a pressing issue until the Easter special, where the Doctor was told that someone would knock 4 times and then he would die.
Everyone assumed that it would be the Master, because of the drumbeat inside his head, which was seemingly confirmed when the Time Lord returned at Christmas. Shockingly, it was the Doctor's friend, Wilf, who inadvertently caused the Doctor to regenerate.
Literally no one was expecting this, which is why it was such a good twist. In Season 12, fans had already had the surprise Master reveal, and most assumed that that was it for the season. However, no one was prepared for "Fugitive Of The Judoon".
The Judoon are a fairly bog-standard monster, so everyone thought the episode would be a quiet family romp. What they weren't prepared for was the return of Jack Harkness, and the reveal of a Doctor who preceded the First Doctor himself!
Over the past few years, the Master has been a part of a lot of incredibly surprising reveals. A special mention must go out to Missy revealing that she was the Mistress, and Agent O's terrifying reveal on a crashing plane in the Season 12 opener.
However, the first Master reveal was amazing, simply because the episode had been fairly simple so far. When Professor Yana revealed his fob watch, though, that was when everything changed. The kind old man was gone, and the Master had returned.
Surprisingly, both Jack and the Face of Boe made their Doctor Who debut in Season 1, although they never actually met. The Face of Boe had a small role, which got bigger and bigger over the course of the first 3 seasons, whereas Jack was a bonafide companion.
In Season 3, the Face of Boe sacrificed his life to save the people trapped on the Motorway, just before telling the Doctor his greatest secret. When Jack returned later on in the same season, he told the Doctor that he used to be known as the Face of Boe when he was younger...
This moment actually served as a double twist. Actress Jenna Coleman had just been announced as the Doctor's next companion, starting after the Ponds' departure. So, viewers were astonished to see Coleman appear in the Season 7 premiere.
Over the course of the episode, fans fell in love with Oswin Oswald. Just as it looked like the Doctor would rescue her in time, however, it was revealed that she was actually a Dalek. This meant that she couldn't possibly be the next companion, which was incredibly exciting.
In episodes 5 and 6 of the show's sixth season, the Eleventh Doctor, Amy and Rory visited a monastery turned mining facility in the future. The factory mined acid, and so the worked used clones of themselves to minimize the loss of life.
This was a good idea in theory, except that the material they used to make the clones, the Flesh, was sentient. The clones developed a mind of their own and staged war on their twins. At the end of the two-parter, Amy herself was revealed to be a Ganger, and had been since before the season began.