This is a huge spoiler and concerns the casting of the finale episode. Only click if you don't mind this being spoiled.
The photo below shows Tennant along with Simm (as we've been expecting) and ex-Bond actor, Timothy Dalton in some very Gallifreyan robes. Dalton has been rumoured to have been cast for a while and this photo seems to confirm it. The big question is, who is he? and what does this mean?
For more finale spoilers, check our our preview page here.