Stan is an elementary school student who commonly has extraordinary experiences not typical of conventional small-town life in his fictional hometown of South Park, Colorado.

While Parker and Stone portray Stan as having common childlike tendencies, his dialogue is often intended to reflect stances and views on more adult-oriented issues and has been frequently cited in numerous publications by experts in the fields of politics, religion, popular culture and philosophy.

Prior to season 22, Stan lives in South Park at 260 Avenue de los Mexicanos with his parents Randy and Sharon Marsh and his sister Shelly.

During this period, Randy, who has an advanced degree in geology, works for the federal government at an earthquake monitoring facility, and Sharon is a secretary at Tom's Rhinoplasty, a plastic surgery clinic.

[2] Whereas Kyle, his best friend, is the only Jewish boy in the main cast, Cartman is an obese, racist, sociopath, and Kenny is poverty-stricken (and in early seasons prone to suffer violent deaths), Stan was originally the everyman, described as "a normal, average, American, mixed-up kid".

[9] Stan is considered particularly attractive by the girls in the class, which is a subtle joke as all of the fourth-grade boys, besides Cartman and the two disabled children (Timmy Burch and Jimmy Valmer), use the exact same model before hair, clothing, and skin color are added.

In many episodes, Stan contemplates ethics in beliefs, moral dilemmas, and contentious issues, and will often reflect on the lessons he has attained with a speech that often begins with "You know, I learned something today...".

[10] An unnamed precursor to Stan first appeared in the first The Spirit of Christmas short, dubbed Jesus vs. Frosty, created by Parker and Stone in 1992 while they were students at the University of Colorado.

[5] He is amused by bodily functions and toilet humor,[5] and his favorite television personalities are Terrance and Phillip, a Canadian duo whose comedy routines on their show-within-the-show revolve substantially around fart jokes.

[31] But the premiere of the second half of the season episode "Ass Burgers" resolved the arc, as Stan was erroneously diagnosed with Asperger's syndrome, and discovers Jameson Irish Whiskey cures cynicism.

[32] In 2014, Stan was ranked by IGN at third place on their list of "The Top 25 South Park Characters", commenting that he "often acts as the voice of reason in the midst of the show's insane events, and in many ways he's more mature than his father Randy".

[34] Stan frequently offers his perspective on religion,[35] and he was at the center of one of the most controversial episodes of the series,[36] "Trapped in the Closet" (season nine, 2005), where he was recognized as the reincarnation of Scientology founder L. Ron Hubbard before denouncing the church as nothing more than "a big fat global scam".

[37] In the show's 26 seasons, Stan has addressed other topics such as homosexuality,[38][39] hate crime legislation,[40] civil liberties,[27] parenting,[41] illegal immigration,[42] voting,[43] alcoholism,[41] and race relations.

[44] His commentary on these issues have been interpreted as statements Parker and Stone are attempting to make to the viewing public,[41] and these opinions have been subject to much critical analysis in the media and literary world.