Among the four people, Stan is a prominent skeptic and often comments on fashion trends. There are obvious performances in the episodes of S4E07, S5E04, S6E 15. Sometimes Kyle becomes suspicious and Stan becomes gullible, such as the episode of S9E 12. Stan and Kyle are not interchangeable, but they are very similar. Although Stan is an autobiography summarized by Trey Parker, Kyle is a representative of matt stone. In fact, Stan is as big a fan of the Denver Broncos as Parker.

Stan had a girlfriend, Wendy Testa Burger, who threw up when talking to her, but they broke up in the seventh episode S7E 14. Wendy is Token's girlfriend again. However, in the episode S 1 1E 14, Stan and Wendy got back together, and then they seldom spoke out.

Stan is the son of Randy Marsh, a geographer in the US Geological Survey, and Sharon Marsh, a waitress in Tom's rhinoplasty clinic. One of his sisters, Shelley, often bullied him and called him "shit", named after Trey Parker's sister (or younger sister). There is also a gay male dog named Sparky, who once kept a "killer goldfish".

As a geographer, his father is also a Nobel Prize winner and a former youth band member. Stan also has a grandfather in a wheelchair. His name is always Stan Billy and he begged Stan to kill him. Stan is also the nephew of Kimble (the hunter in the hat in town) (Kimble is Sharon's brother).

Stan is wearing a red cotton ball cap with a red edge and a blue background, a brown coat, blue trousers and red gloves. Stan seldom takes off his hat. Below is fluffy black hair. In the fourth episode S4E 17, when Butters is drawing cartoon characters of several of them, Kyle points out that Stan's eyes are blue.