South Park is an American adult animated television series created by Trey Parker and Matt Stone for the Comedy Central television network. The ongoing narrative revolves around four boys, Stan Marsh, Kyle Broflovski, Kenny McCormick, and Eric Cartman and their bizarre adventures in and around the fictional Colorado town of South Park. The town is also home to an assortment of characters who make frequent appearances in the show, such as students and their family members, elementary school staff, and recurring characters.

Stan Marsh is portrayed as the everyman of the group, as the show's official website describes him as "a normal, average, American, mixed-up kid." Kyle is the lone Jew among the group, and his portrayal in this role is often dealt with satirically. Stan and Kyle are best friends, and their relationship, which is intended to reflect the real-life friendship between South Park creators Trey Parker and Matt Stone, is a common topic throughout the series. Cartman—loud, obnoxious, and obese—is sometimes portrayed as the series' antihero and his antisemitic attitude has resulted in an ever-progressing rivalry with Kyle. Kenny, who comes from a poor family, wears his parka hood so tightly that it covers most of his face and muffles his speech. During the show's first five seasons, Kenny died in almost every single episode before returning in the next without explanation.

Stone and Parker perform the voices of most of the male South Park characters. Mary Kay Bergman voiced the majority of the female characters until her death in 1999. Eliza Schneider (1999–2003), Mona Marshall (2000–present), April Stewart (2004–present), and Kimberly Brooks (2008–present) have voiced most of the female characters since. A few staff members such as Jennifer Howell, Vernon Chatman, John Hansen, and Adrien Beard have voiced other recurring characters.

Following the success of the 1995 short Jesus vs. Santa, creators Trey Parker and Matt Stone conceived a plan to create a television series based on the short, with four children characters as the main stars. The series was originally set up at 20th Century Fox Television for its primetime premiere on FOX, which previously commissioned Parker and Stone to develop the short. However, FOX was not pleased with the show's inclusion of Mr. Hankey, a talking poo character, and felt it wouldn't bode well with viewers. The network's executives also said that placing kids as the stars could not be as funny and popular as it would with the grown-ups and families, like The Simpsons and King of the Hill.

As a result, Parker and Stone broke off relations with FOX and took the series somewhere else. They pitched the series to MTV and Comedy Central, and decided it was best suited for the latter, fearing the former could turn it to a more kid-friendly show later on. Comedy Central agreed to pick up the series, and the premiere episode, "Cartman Gets an Anal Probe", debuted on the network on August 13, 1997, while Mr. Hankey would debut in the tenth episode, "Mr. Hankey, the Christmas Poo".

In tradition with the show's cutout animation style, the characters are composed of simple geometrical shapes and uninflected patches of predominantly primary colors. They are not offered the same free range of motion associated with hand-drawn characters, as they are mostly shown from only one angle, and their movements are animated in an intentionally jerky fashion. Ever since the show's second episode, "Weight Gain 4000", all the characters on the show have been animated with computer software, though they are portrayed to give the impression that the show still utilizes the original technique of cutout animation.

Stone and Parker voice most of the male South Park characters. Mary Kay Bergman voiced the majority of the female characters until her death in 1999, near the end of the third season. Eliza Schneider and Mona Marshall succeeded Bergman in 1999 and 2000 respectively, with Schneider leaving the show in 2003, after the seventh season. She was replaced by April Stewart, who, along with Marshall, continues to voice most of the female characters. Bergman was originally listed in the credits under the alias Shannen Cassidy to protect her reputation as the voice of several Disney characters. Stewart was originally credited under the name Gracie Lazar, while Schneider was sometimes credited under her rock opera performance pseudonym Blue Girl.

Some South Park staff members voice other recurring characters; supervising producer Jennifer Howell voices student Bebe Stevens, writing consultant Vernon Chatman voices an anthropomorphic towel named Towelie, and production supervisor John Hansen voices Mr. Slave, the former gay lover of Mr. Garrison. South Park producer and storyboard artist Adrien Beard, who voices Tolkien Black, the only African-American child in South Park, was recruited to voice the character "because he was the only black guy [in the] building" when Parker needed to quickly find someone to voice the character during the production of the season four (2000) episode "Cartman's Silly Hate Crime 2000".