Parker was born in Denver, Colorado, the son of Randy (a geologist) and Sharon (an insurance broker). The two share the first names and occupations of South Park characters Randy and Sharon Marsh. He has an older sister named Shelley, which is also the name of Stan Marsh's older sister. Parker grew up in the Conifer, Colorado area, and attended Berklee College of Music before transferring to the University of Colorado, where he majored in music.
In 1992, Parker and Stone created Jesus vs. Frosty. It included four boys, Stan Marsh, Kyle Broflovski, Kenny McCormick and Eric Cartman. Both Jesus vs. Frosty and Cannibal! The Musical were made while they were students at the University of Colorado film school, studying under both Stan Brakhage and Jerry Aronson. Fox executive Brian Graden saw Cannibal! The Musical, and commissioned Parker and Stone to create Time Warped, a show similar to Cannibal!, but on a weekly basis. After two pilot episodes, the show was dropped.
After the duo released Cannibal! The Musical, they were asked to make another animated short. They came up with two worthwhile ideas; one a sequel to Jesus vs. Frosty, entitled Jesus vs. Santa, and one about a character that would later be recurring in South Park, Mr. Hankey. They chose to write about the four boys, and their decision ultimately opened the door for them to present a show, South Park, to Comedy Central. Stone and Parker produced 13 episodes for season 1. South Park is currently still under contract to produce new episodes through 2011.
In 1997, they also released Orgazmo, a movie rated NC-17. In 1998, they starred in (but did not write or direct) BASEketball, another feature film, while being renewed for a second season of South Park. In 1999, Parker and Stone made South Park: Bigger, Longer & Uncut, which gave the series a new level of prominence. He was nominated for an Academy Award as the co-writer of one of the film's songs, "Blame Canada," but did not win. In 2001, the duo announced they would do 39 shorts between the lengths of 2 and 5 minutes. Although originally thought to be South Park related, they decided they would do something different. The result was the shorts Princess. The content was so extreme that it was cancelled after two shows aired. In 2001, they also created That's My Bush!, another television series. Despite great reviews, the show was cancelled after one season for the cost per episode. In 2004, they made a film, titled Team America: World Police. The film was not considered a box-office success, grossing 51 million dollars in theaters, despite largely positive reviews (78% fresh rating on RottenTomatoes.com). As of 2010, South Park is in its fourteenth season.
Parker is also a member of the band DVDA with Stone, for which he plays keyboards and sings. DVDA's songs have appeared in many of the duo's productions. They include Orgazmo,BASEketball , South Park: Bigger, Longer & Uncut, and Team America: World Police.
Trey claimed to have been on acid with Matt Stone at the time of the 2000 Academy Awards, where they wore dresses popularized by Jennifer Lopez and Gwyneth Paltrow at previous awards shows.[
On September 28, 2007, Parker and Stone acquired the rights to the Canadian-made Kenny vs. Spenny, which premiered November 14, 2007 on Comedy Central with ten old and new episodes.
In April 2010, Trey Parker and Matt Stone received a "warning" for allegedly representing the Prophet Muhammad in a bear costume: "We have to warn Matt and Trey [South Park creators] that what they are doing is stupid and they will probably wind up like Theo Van Gogh for airing this show." It was revealed in the next episode that the person in the bear costume was really Santa Claus and not the Prophet Muhammad.
Parker and Stone have collaborated with Avenue Q composer Robert Lopez on a musical about Mormons; it is titled Book of Mormon, and stars Andrew Rannells and Josh Gad. It has been produced by Scott Rudin and Anne Garefino. It opened at the Eugene O'Neill Theatre on March 24, 2011, following previews from February 24, 2011.
On July 27, 2010, a stage version of Cannibal! The Musical will make its West End premiere at the Leicester Square Theatre. It will be produced by Frazer Brown