A Knight on Doctor Who

Sir Derek Jacobi joins cast to save humanity.

Sir Derek Jacobi is to guest star in series three of Doctor Who.

Back in 2003, Sir Derek appeared, in the online animated adventure Scream of the Shalka, in which David Tennant featured briefly.

According to the production team, Jacobi will play the Professor, a character caught in a desperate bid to save the human race, in an episode of the upcoming series.

The 68-year-old actor, who was knighted in 1994, is perhaps best remembered for his role in the acclaimed BBC drama series I, Claudius. As well as being a founding member of the National Theatre, his Film roles have included parts in The Day of the Jackal, The Odessa File and Gladiator.