Michelle Ryan (born 22nd April 1984), a London-born actress, played Lady Christina de Souza in Planet of the Dead.
Born only a few weeks after Colin Baker's debut as the Doctor, Ryan is best known in the UK for her work on the soap opera EastEnders, and for co-starring in Steven Moffat's miniseries, Jekyll. She also played Nimueh in BBC One's fantasy drama Merlin. In North America, Ryan is best known for portraying a reimagined version of iconic TV superhero Jaime Sommers on the short-lived NBC series Bionic Woman in 2007.
Reportedly, Ryan was considered a candidate for companion after Billie Piper (who she subsequently co-starred with in a TV production of Mansfield Park) left the series, and in January 2009, before it was announced that she had been cast in the special, there was considerable media speculation suggesting that she had been, or will be cast as the companion to the upcoming Eleventh Doctor, a fact that, as of March 2009, has yet to be confirmed; according to BBC casting announcement, there is no indication that she appears in the special that follows Planet of the Dead. BBC Audio have confirmed that Michelle is to read the Tenth Doctor audio exclusive story The Rising Night written by Scott Handcock.