10 Doctor Who Moments That Broke The Fourth Wall

10. K9 Mark II (The Invasion Of Time)

As the longest-serving Doctor we've ever had (with seven years under his belt), Tom Baker's cheeky, quick-witted incarnation had plenty of time to squeeze in a few fourth wall breaks throughout his tenure, so that's exactly what he did.

In the closing moments of 1978's The Invasion Of Time, Baker's Doctor bids farewell to companions Leela and K9 before heading back to the TARDIS, alone, and a little downbeat. Before long though, he retrieves an enormous box from the back of his ship - a box that contains an upgraded, brand-new version of his beloved robot mutt.

Appearing quite chuffed at the fact that he's managed to replace one of his friends with relative ease, the Doctor then looks straight into the camera, flashing us viewers one of the biggest, cheesiest grins in television history.

This is actually the second fourth wall break in this serial, following an earlier moment where the Doctor mocks his over-reliance on the sonic screwdriver. Here though, it's just a very happy Time Lord and his dog!