Phil LaMarr was born in Los Angeles, California. He is a graduate of Harvard-Westlake School in North Hollywood and Yale University, where he helped found the improv comedy group Purple Crayon. One of his biggest roles at Yale was the title character in the British comedy Trevor. After graduating in 1989, LaMarr became a member of the award-winning sketch and improv comedy group The Groundlings. He also studied improv at Second City and at the ImprovOlympic in Chicago with Del Close. He has also improvised with Cold Tofu and Off the Wall. Perhaps his greatest early role was one of the many hosts on the Ontario, Canada children's series Polka Dot Door.
His early film jobs arose from connections from his improv and college years. For example, LaMarr appeared in the film It's Pat (1994), written by friends from the Groundlings, and he appeared in Bio-Dome because the director was a friend from college. However, his big break came in a small but memorable role in Pulp Fiction as Marvin. (He would later reprise the role in a MAD TV sketch parodying the film.)
LaMarr gave voice to the title character in the Cartoon Network animated series Samurai Jack, which started in 2001 and was canceled in 2004. The show was about a time-displaced samurai living in a dystopian future.
LaMarr's television credits include a starring role on Justice League as Green Lantern, a major role as Hermes Conrad and various other characters on Futurama, the title roles on Static Shock, and guest starring roles on Cold Case, Eve, Reno 911!, the British version of Whose Line is it Anyway?, Without A Trace, Invader Zim, The Bernie Mac Show, NYPD Blue, Living Single, The Fresh Prince of Bel-Air, Murphy Brown, and Family Guy. In season three of Mind of Mencia, he played the ghost of Johnnie Cochran. LaMarr reprised his role as Hermes Conrad in the Futurama movies Bender's Big Score, The Beast with a Billion Backs, Bender's Game, and Into the Wild Green Yonder. He also voices Jackie Khones, a recurring character in Foster's Home for Imaginary Friends, Carver Descartes on The Weekenders, and several characters in the critically acclaimed Afro Samurai. He additionally voices Jazz, Omega Supreme, Oil Slick, and Jetstorm on Transformers: Animated. LaMarr's newest role will be voicing Gambit and Trask in the new animated tv show, Wolverine and the X-Men. Recently LaMarr provided the voice for Nautolan Jedi Master Kit Fisto in Star Wars: The Clone Wars on Cartoon Network; he also played Amit Noloff, a one time character, and a Tactical Droid. He also had a major role in Class of 3000 as Philly Phil.