Jimmi Simpson (b. 1975) plays the character Mary Lightly on the series Psych.
Simpson is an American actor who has also appeared in the miniseries Rose Red and episodes of 24, Carnivàle, My Name Is Earl, It's Always Sunny in Philadelphia, CSI: Crime Scene Investigation, and Late Show with David Letterman (uncredited). He also appeared in movies, such as Loser, Final Draft, D.E.B.S., Herbie Fully Loaded, Stay Alive, A Quiet Little Marriage, The Mother of Invention, The Invention of Lying, Taking Chances, and Date Night. He'll also be appearing in the future movie The Big Bang.