The feature-length 50th anniversary extravaganza The Day of the Doctor was full of surprises but nothing could've prepared fans both young and old for the shock return of Tom Baker. The Fourth Doctor actor was introduced as a mysterious character known only as 'the Curator' and it's alluded that he's a future incarnation of the titular Time Lord who retires and revisits some of his favourite faces. A scene flooded with nostalgia that made the landmark festivities even more special.