M is for... Matheson, Rex

CIA agent Rex Matheson was involved in what ought to have been a fatal car accident one night, when a metal pole passed through his heart. At the Emergency Room he discovered that he was not the only person to have had a miraculous escape. Across the globe, people had suddenly stopped dying. The event became known as "Miracle Day".

Investigating, he discovered references to an organisation called "Torchwood", and so travelled to Wales to find its surviving members. His visit to the remote home of Gwen Cooper coincided with an attack on her and her family by some unknown agency. Captain Jack Harkness turned up and helped save them. He and Gwen were then arrested by Rex and extradited to the US, but attacks on the Torchwood team continued when Jack was poisoned on the flight by one of Rex's own colleagues.

Already immortal, Jack had been rendered mortal by the Miracle Day phenomenon. With other members of the CIA implicated in the plot, including his own superior, Rex was forced to go rogue and become a temporary member of Torchwood, along with colleague Esther Drummond and a doctor named Vera Suarez.

Together they uncovered the "Categories of Life" programme, which saw some of the dying being cremated alive due to the drain on medical resources which the event was causing. At the same time, certain big pharmaceutical companies were exploiting it. It later transpired that they were behind the event. Rex leaked a video of the Category camps to the world media.

A trio of Italian-American families had obtained samples of Jack's blood back in the 1930's, and had fed it into a natural phenomenon deep beneath the Earth's surface, which they called "the Blessing". This was generating the biological field that was keeping everyone from dying.

Rex helped Jack and Gwen break into the LA HQ of Phi-Corps to find evidence that they had known of the Miracle Day in advance - and rescued them when they were captured. After arguing with Esther and Gwen for keeping in touch with family - putting them at risk - he visited his own estranged father.

After revealing publicly his boss's involvement with the Three Families, Rex and Esther were able to resume their CIA roles.

It was realised that a second infusion of Jack's blood into the Blessing would reverse the process. An attack was planned, with the team striking both ends simultaneously in Buenos Aires and Shanghai. Rex smuggled Jack's blood into the Argentine location within his own body, having taken a blood transfusion from him. He killed one of the Family leaders moments after the Miracle ended, with the Blessing collapsing. Esther had been killed and, at her funeral, a CIA member who had been secretly helping the Families for years shot and killed Rex - only for him not to die. His exposure to Jack's blood had rendered him immortal.

Played by: Mekhi Phifer. Appearances: Torchwood Series 4: Miracle Day (2011).

• Phifer first came to prominence working alongside Alex Kingston on medical drama ER.