Michelle Ryan

 The BBC have announced that former EastEnders star Michelle Ryan will guest star in Doctor Who's Easter special.

She will play the mysterious Lady Christina de Souza in the special episode, entitled "Planet of the Dead" – ‘I'm a huge fan of Doctor Who and very excited to be joining David Tennant and the Doctor Who team’, she has said.

Michelle Ryan is best known for playing Zoe Slater in the BBC One soap and starring in the American remake of Bionic Woman. More recently she has been seen playing the part of the evil Nimue in Merlin.

Recently, there has been speculation that she could be cast as The Doctor's new assistant, when Tennant's replacement, Matt Smith, takes on the role next year. It is not known whether this appearance rules her out of that role – However, as Catherine Tate's character Donna Noble first appeared in a Doctor Who Christmas special 15 months before she returned as The Doctor's assistant nothing can be ruled out.

Ryan has been reported at saying: ‘It is such a fantastic show and I can't wait to get started’. And executive producer and writer Russell T Davies has said: ‘Michelle is one of the most sought-after young actors in the country and we are delighted to announce that she will be joining the team. As always the script is being kept strictly under wraps. However, we can reveal that Lady Christina is a woman with a mysterious past who's going to have a huge impact on The Doctor’.