Rex Matheson

Agent Rex Matheson, portrayed by Mekhi Phifer, is a fictional character in the BBC television programme Torchwood, a spin-off from the long-running series Doctor Who. Phifer was one of three American actors to join Torchwood in its fourth series, Torchwood: Miracle Day (2011), as part of a then-new co-production between Torchwood's British network, BBC One, and its American financiers on US premium television network Starz.

Rex is introduced by series producer Russell T Davies as a means of introducing new American audiences to the established world of Torchwood. Within the series' narrative, Rex is a high-flying agent for the Central Intelligence Agency (CIA) who begins to investigate Torchwood after being personally affected by a global supernatural event. Rex's role as a second male hero in the series leads him to clash with returning male lead Captain Jack Harkness (John Barrowman). He eventually becomes immortal in the same vein as Harkness.