The 4 main characters in the animated series South Park are Eric Cartman, Stan Marsh, Kyle Broslofski and Kenny McCormick. See those articles for details.

Other characters with their own articles are Butters and Mr. Garrison.

There are several minor South Park characters.

Table of contents
1 Family members
2 School (adults)
3 School (children)
4 Misc

Family members

Mrs. Cartman

Lianne Cartman is (supposedly) the mother of Eric, and puts up with his constant whining with remarkable patience, never once seeming to become angry or raise her voice. Despite her sweetness, she is a hermaphroditic porn-queen and prostitute. Quite early on, it was revealed that Mrs. Cartman was actually Eric's father.

Gerald and Sheila Broslofski, and Ike

The Jewish parents of Kyle, Gerald and Shiela are also the adopted parents of baby Ike Moisha, himself of Canadian descent.

Gerald is a lawyer, and once made money for suing literally everyone in the town for sexual harassment.

In the movie, South Park: Bigger, Longer & Uncut, Sheila became enraged that a Canadian film had introduced Kyle to "naughty language", and sparked a war between the United States and Canada.

Randy and Sharon Marsh, Shelley and Grandpa

Randy and Sharon Marsh are the parents of Stan, and his exceptionally violent sister Shelley, Grandpa Marsh who on episode 106: Death keeps asking Stan to kill him.

The McCormicks

Kenny's family, the McCormicks, are exceptionally poor, in part because Kenny's father, Stuart, is an alcoholic, a fact that Cartman never lets Kenny forget. The McCormicks have been through a lot of grief over the course of the series, in large part due to the many deaths of their son.

School (adults)

See also: Mr. Garrison.

Chef

Jerome 'Chef' McElroy is one of very few black characters in South Park, and the chef at the local school. A stereotyped character, Chef is obsessed with sex and somewhat promiscuous. He is however a talented singer.

Quote: Let's all go home and find a nice white woman to make love to.

Ms. Choksondik

After Mr. Garrison was temporarily suspended from teaching duties, he was replaced by Ms. Choksondik, who was most notable for her implausibly large, saggy breasts. Ms. Choksondik inexplicably died in the middle of the sixth season, and Mr. Garrison eventually replaced her as the fourth grade teacher.

Mr. Mackey

Mr. Mackey is the school guidance counselor. He is best known for his simplistic attitude towards drugs (and his catchphrase, "drugs are bad, mmm'kay?"), a parody of Just Say No campaigns; he never gives any reason why drugs are bad.

School (children)

See also: Eric Cartman, Stan Marsh, Kyle Broslofski, Kenny McCormick, Butters Stotch.

Timmy

Timmy is a handicapped child who can only say his own name, and is confined to a wheelchair. Nevertheless, in one episode he was part of a successful band, the Timmy and the Lords of the Underworld.

Token Williams

Token Williams is the only black child in the main characters' class. Cartman was once imprisoned for a hate crime after he assaulted Token.

Wendy Testaburger

Wendy was, for a long time, the object of Stan's affections; however he would throw up out of nervousness whenever she came near him.

Bebe Stevens

Bebe is Wendy's blonde-haired best friend. She once had a "relationship" with Kyle, but after she couldn't take the "codependency", she started another "relationship" with Clyde.

Tweek

Tweek is a particularly nervous child, apparently as a result of drinking too much coffee. He is inclined to scream at the slightest provocation, or complain of "too much pressure!" when anyone asks him to perform the slightest task.

Clyde

Clyde is the brown-haired boy who is part of the group, but doesn't maintain any major presence.

Craig

Even though he hangs out with the boys, Craig is the one who is (in)famous for flipping off people.

Jimmy

Like Timmy, he is handicapped, but he uses crutches to walk. Despite having a stuttering problem, he likes to perform stand-up comedy.

Misc

Big Gay Al

Big Gay Al is a stereotyped gay man. He runs an animal farm for gay animals who have been rejected by homophobic pet owners. He also appeared in South Park: Bigger, Longer & Uncut, entertaining U.S. troops.

Jimbo and Ned

Jimbo Kerns and Ned Gerblansky are both obsessed with killing animals, circumventing anti-hunting laws by claiming self-defense - and thus, always exclaiming "It's coming right for us!" - before shooting some animal that was not, in most cases, coming right for them.

Ned lost his voice due to cancer, and is forced to speak with an electronic voicebox. He also lost an arm in the Vietnam War.

Officer Barbrady

Officer Barbrady is the town's only policeman, and is particularly inept. He was illiterate until forced to learn to read to solve a crime. He then read Atlas Shrugged by Ayn Rand, an experience that made him regret ever learning to read.

Doctor Mephisto

Doctor Mephisto is a stereotyped mad scientist, who specialises in genetic engineering, and like Frankenstein, proceeds to create strange creatures without stopping to consider whether he should.

He often seems interested in genetically engineering creatures with more than one anus - an apparent parody of the (real world) creation of a mouse with a human ear growing from its back.

He is a member of NAMBLA, the North American Marlon Brando Look Alikes.