10 Doctor Who Fan Theories That Will Blow Your Mind

This theory compliments and supports the previous one, but is also interesting to look at in its own right, since it could change how you view a good majority of the Doctor's adventures.

As previously mentioned, Silents are creatures that exist to remain unseen. You can look at them, but as soon as you look away, you forget they were ever there. This unique trait means that there could be Silents littered throughout the Doctor Who universe, and neither the Doctor nor his companions would know. So what if there was one on the TARDIS at some point?

The most likely point in time for this would be Series 5. In The Lodger, Amy is left alone on the TARDIS while the Doctor investigates an alien threat. At numerous points throughout the episode, she appears to be looking off-camera at something, before carrying on and acting as though everything is fine. The most notable of these instances occurs around 21 minutes into the episode, when Amy audibly gasps at something off-screen...

...before appearing completely fine seconds later - almost like she's just forgotten something.

Plus, if there was a Silent aboard the TARDIS during The Pandorica Opens, then this makes it even easier to explain the last theory. When a person looks at a Silent, the creature can tell them to do something, but when they look away, they forget about the creature, but still remember the command. What if River was constantly observing a Silent who told her to blow the TARDIS up, an order that she still retained, despite forgetting who gave her it?

It's unlikely there's still a Silent aboard the TARDIS during the show's current run, but it's fun to look back at certain episodes with this theory in mind.