Can't wait until Nov. 23 to see worlds collide in Doctor Who's anniversary special, "The Day of the Doctor"? Here's a sneak peek, featuring a lot of fez action, a mystery involving famous paintings that have a Monty Python-esque problem... and a special guest star.

This clip just appeared in the UK as part of the annual Children in Need charity event. If you're watching this outside the UK, you are still highly encouraged to donate to the charity event here.