The Doctors of "Doctor Who" -- screenshot from "The Day of the Doctor"
The Doctors of "Doctor Who" -- screenshot from "The Day of the Doctor" Doctor Who/YouTube

“Doctor Who” is not the Doctor’s real name, despite how Missy (Michelle Gomez) insisted it was. Only a few people know – or can pronounce – the Doctor’s (Peter Capaldi) name, but many have their own theories.

Spoilers for the most recent episode of the show, as well as its past episodes, are discussed below.

In the recently aired season 10 episode 11 “World Enough and Time” (aired Sunday in Australia on the ABC), Missy, playfully imitating the Doctor, called herself Doctor Who. When Bill (Pearl Mackie) why she claimed it’s his name, Missy said he chose it himself to sound mysterious. Missy acted so self-aware of the viewers’ thinking in that episode that she, perhaps accurately, called Bill and Nardole (Matt Lucas) the disposables Exposition and Comic Relief. The episode, however, got dark so fast, ending in a cliffhanger that left fans in shock.

Back to the Doctor’s real name, showrunner Steven Moffat said that if they were going with continuity, then the character’s name is Doctor Who. He explained to Radio Times that the Doctor had introduced himself as such numerous times. The Classic Who Doctors had called themselves as Doctor Who, and even the revived version’s Christopher Eccleston (Ninth Doctor) was billed as that. However, Moffat refused to believe so, even if, he said, he’s canonically wrong.

As the past episodes have proved, his name is significant for a number of reasons. It has been a mystery since the UK show first aired in 1963, and it looks like it will remain that way forever. Even Capaldi, the Twelfth and current incarnation of the Doctor, has his own theory as to what it is.

Peter Capaldi’s name theory

In April, a young fan asked Capaldi at the show’s season 10 launch if he knew the Gallifreyan Time Lord’s real name. The 58-year-old Scottish actor admitted that he had no answer, but he had a very good guess.

“But I think he does have a real name… I think ‘the Doctor,’ like everything about him, is a thing he’s come up with to make himself understood by human beings,” he said (via Digital Spy). “I don’t think human beings could even really say his name. But I think we might be able to hear it. At a certain frequency. If the stars are in the right place, and you heart’s in the right place, you’ll hear it.”

It’s a beautiful theory and one that is close to canon explanations that his true name, which has 38 syllables, is unpronounceable by humans. Given that his name is Gallifreyan and even the written characters are difficult to read by earthlings, it’s a valid explanation.

The Doctor’s real name is the ‘answer to everything’

In the 1979 novel “The Hitchhiker’s Guide to the Galaxy,” a supercomputer named Deep Thought was asked the “answer to the ultimate question of life, the universe and everything.” After millions of years of calculation, it came up with “42.”

And according to a theory, the supercomputer was referring to the Doctor. There were fans who speculate that the answer found in the novel and the question in the sci-fi show – “The oldest question in the universe, which must never be spoken and must always be kept secret” – is one and the same.

Theta Sigma

This one isn’t actually a theory but more of a canon. It’s not his full name, but his nickname when he was at the Time Lord Academy in his planet. It is more than that, though. Apparently, Theta Sigma, or Θ Σ , is just part of his full name, like Romana (a Gallifreyan Time Lady and companion to Fourth Doctor) was short for Romanadvoratrelundar.


In a 1980 comic book (image provided by a Redditor), it was written that his real name is ∂³∑x². Another Reddit user, WorstGabeNA, responded and actually did the math of the Doctor’s name. As it was succinctly explained in his equation, the value of the equation would equal his age.

“Meaning, according to the time-part, that if we know the positioning of The Doctor, we can not only fully understand the name of the Doctor, but also his age,” the Redditor wrote. “As a side note, the time in which he is in, might be the time in the equation, although it still might not be part of his name.”

The Doctor’s real name is his timeline

One of the most fascinating theories about the Doctor’s name is that it’s his own timeline. According to this theory, his name, written in circular Gallifreyan, is the whole story of his life. Therefore he does not want to broadcast it to everyone in case his enemies take advantage of it. Imagine if the Daleks got hold of his name, they would know how the Doctor’s life would end or had begun. Needless to say, they would have had a great advantage over him.


With the mysteries surrounding the Doctor’s real name, almost everyone can agree that it would be disappointing if the Doctor’s real name turned out to be just Fred. The Doctor previously claimed it was Basil, but one thing is certain about the time traveller: The Doctor lies.

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