Mekhi Phifer (/mɛˌkaɪ ˈfaɪfər/ meh-KY FY-fər; born December 29, 1974) is an American actor. He portrayed Dr. Greg Pratt on NBC's long-running medical drama ER until 2008 and had a co-starring role opposite rapper Eminem in the 2002 feature film 8 Mile. He was a recurring cast member on the Fox crime show Lie to Me in the role of Ben Reynolds before season 3, and also starred as CIA officer Rex Matheson in Torchwood: Miracle Day.