10 Doctor Who Mysteries With The Worst Possible Answers

2. What's Inside Room 11?

Set in a mysterious hotel where each room contains someone's darkest fears, The God Complex is one of the highlights of Doctor Who's sixth series. It's largely a standalone tale, but one moment in particular led to years of fan speculation.

When the Doctor discovers Room 11, he peers inside, but we the viewers don't get to see what's there. Instead, the Doctor smiles wryly and says "Of course. Who else?"

So who was it? Who did the Doctor fear most in the universe? River Song? The Master? Michael Grade?!

The occupant of Room 11 was revealed two years later in the Eleventh Doctor's final story, The Time of the Doctor – and it wasn't what anyone was expecting. Inside the Doctor's room was... a crack in space and time?

It's a reveal that so clearly was not the original intention that it just doesn't land as authentic. In fact, it's glaringly obvious that there was no original intention – clearly Moffat thought he could just make something up later, which explains why, in The God Complex, the Doctor describes the crack in time that's apparently inside his room as a "who".

That's a What, not a Who!

So the thing the Doctor fears most is... all of the Time Lords? The restarting of the Time War? Over a decade later, we're still not sure.