"The Lazarus Experiment" is the sixth episode of the third series of the revived British science fiction television series Doctor Who. It was broadcast on BBC One on 5 May 2007 and stars David Tennant as the Tenth Doctor and Freema Agyeman as Martha Jones. In the episode, Professor Richard Lazarus (Mark Gatiss) demonstrates an experiment at his laboratory near Southwark Cathedral in Southwark where he renews himself into a younger-looking man. The effects on Lazarus' DNA causes him to change into a giant creature that sucks the life force from other victims.