Doctor Who: What is the Doctor's real name?

What is the Doctor's real name? Matt Smith and Jenna Coleman from The Name of the Doctor in season 7.
The Eleventh Doctor Matt Smith (above) reveals the nature of his true name to companion Clara (Jenna Coleman). (Image credit: BBC)

The Doctor's real name has been one of the most persistent mysteries in all of Doctor Who. The sci-fi series has hinted at the Doctor's true identity so many times, but the BBC has never given us an answer to what is apparently the oldest question in the universe: “Doctor who?” 

Whether it's John Smith, Theta Sigma, or the many fake identities the Doctor gives using their psychic paper, the Doctor has worked pretty hard to keep their real name a secret. Oh, and there's also all those rather threatening titles their alien enemies have given them like "Oncoming Storm" or "Destroyer of Worlds," too.

The Doctor's real name may have been kept a secret, but there are still some possible candidates. 

Here are the Doctor's most commonly used names!

Is the Doctor's real name just the Doctor?

Probably not. 

The Eleventh Doctor (Matt Smith) specifically told Clara (Jenna Coleman) that he chose his title in The Name of The Doctor, where he said taking the name was like making a promise. Clara later told the Time Lords through the crack in time that whatever the Doctor’s name once was was no longer important. What matters, after all, is what "the Doctor" stands for.

Earlier in the show’s history, the Valeyard, a character created out of several of the Doctor’s “dark sides”, also declared that the Doctor was just an alias the whole time during the trial of the Sixth Doctor (Colin Baker) in The Mysterious Planet story.

What about Doctor Who?

Several of the older Doctors were referred to as “Doctor Who”, either by companions or enemies. A supercomputer called WOTAN referred to William Hartnell’s First Doctor as Doctor Who on several occasions, and the Second Doctor (Patrick Troughton) used the name “Doktor von Wer” (meaning Doctor [of] Who) when he visited 18th Century Scotland.

More recently, Michelle Gomez’s female version of the Master, Missy, claimed that she had learned Doctor Who really was their true name after all, but said they had dropped the “Who” after they felt it was ’too on-the-nose.’ However, the Twelfth Doctor (Peter Capaldi) claimed this was just Missy teasing his companion Bill, even though he never confirmed whether Missy was telling the truth or not.

With this, plus the long-running gag using the show’s title “Doctor, Doctor Who?”, it does seem unlikely that this is the character’s real name after all.

what is the doctor's real name? Missy, from Season 10.

Missy taunts companion Bill Potts about the Doctor's real name. (Image credit: BBC)

Is Theta Sigma the Doctor's real name?

Theta Sigma was the Doctor’s unique nickname when he was studying at the Time Lord Academy on Gallifrey. Although this identified the Doctor from all the other Time Lords at the academy, the Seventh Doctor (Sylvester McCoy) dismisses it as just a nickname in The Happiness Patrol. Drax, the other time lord who recalls the nickname in The Armageddon Factor, isn’t the only person who refers to the Doctor by this name, though!

The nickname was also part of the message that River Song left on the diamond cliff-face on Planet One, the oldest planet in the universe. In the audio drama, Forever, a version of the Doctor from an alternate timeline never gets to leave the planet Gallifrey as a renegade Time Lord, becoming Commentator Theta Sigma instead. 

John Smith

John Smith is one of the Doctor’s most commonly used names. Nearly every single Doctor that we’ve seen so far has used it to date, usually when they need a “normal” name around other humans.

Notable examples include the Tenth Doctor (David Tennant) becoming the schoolmaster John Smith to hide from the Family of Blood, or the Third Doctor (Jon Pertwee) using the name regularly to work alongside UNIT when he was exiled on Earth. The Second Doctor also called himself John Smith when he was interrogated by a German soldier.

The Eleventh Doctor also used the name to pose as his Ganger clone in ‘The Almost People’, and the Twelfth Doctor (Peter Capaldi) adopted it when he went undercover as Coal Hill School’s caretaker.

John Smith is also a favourite name of the Doctor outside of the TV series, cropping up regularly in Doctor Who comic books, novels and audio dramas, even including the sneaky use of “Jane Smith” by the Thirteenth Doctor (Jodie Whittaker). 

what is the Doctor's real name? David Tennant as John Smith in Season 3

David Tennant disguised by the Chameleon Arch as John Smith in Doctor Who season 3. (Image credit: BBC)

It seems unlikely that we will ever truly know the Doctor’s real name. The many possible names we have learned have often been brushed aside or given to the renegade Time Lord by their enemies from across the Whoniverse, or they've just been bare-faced lies. 

With series 12 fundamentally changing the course of history for the Doctor, maybe we will learn once and for all what their true identity is when Doctor Who returns later this year!

Martin Shore
Staff Writer at

Martin is a Staff Writer with, where he produces a variety of articles focused on the latest and greatest films and TV shows. 

Some of his favorite shows are What We Do In The Shadows, Bridgerton, Gangs of London, The Witcher, Doctor Who, and Ghosts. When he’s not watching TV or at the movies, Martin’s probably still in front of a screen playing the latest video games, reading, or watching the NFL.