One of Britain's best known actors, Sir Derek Jacobi, is to guest star in the forthcoming third series of Doctor Who, according to Thursday's Daily Mirror.
The tabloid paper also reveals the name of his character. Click on the spoiler box below to see the details. While the BBC have confirmed Jacobi's involvement, they have neither confirmed nor denied the spoiler which has resulted in much speculation in our forum.
While this is Jacobi's first appearance in televised Doctor Who, he has previously voiced the Master in the six-part animated BBCi webcast Scream of the Shalka, as well as taking a starring role in one of the Dr Who Unbound audio dramas for Big Finish in 2003.
According to the Daily Mirror, Jacobi will appear as a "good guy" called The Professor who helps the Doctor and Martha to save Earth and the human race.