10 Most Unexpected Doctor Who Moments

10. Captain Jack Is The Face Of Boe

Series 3 is often overlooked, which is a shame because it packs some real punches. After the ongoing thread of 'Who is Harold Saxon' (more on that later), fans were left puzzled over another mystery.

How did The Face Of Boe know about The Master and Professor Yana? It seemed as if the show was going to leave that key plot point unresolved, until a scene right at the end of the finale, Last Of The Time Lords, explained all.

As fan-favourite Captain Jack Harkness departs the Tenth Doctor and Martha Jones, he tells them that during his stint with the Time Agency, he had a very interesting nickname: "The Face Of Boe they called me."

Cue shocked expressions from everyone, including The Doctor and Martha. It was such a clever reveal that stunned audiences and what it makes it better, is that all the signs were there but nobody was able to join the dots.

The Face Of Boe was said to have lived for millions of years and watched the universe grow old- and even calls The Doctor an old friend. Jack is immortal but still ages, and would know all about The Master and Yana.

For years, showrunner Russell T. Davies has stated that this all just a theory but during a recent watch-along of New Earth, he seemingly confirmed that the two are the same person.