Being a heavy alcoholic, Stuart is drunk most of the time. He is shown to often argue and abuse his wife, but it appears to go both ways, as in some episodes Mrs. McCormick berates him without direct provocation. Although he and his wife have been shown physically abusing each other, it has never been shown or implied that Stuart abuses his children. When he is sober, he is very loving and caring to his wife. In "Cartman Joins NAMBLA", the two of them decided to have another child. When Kenny, trying to kill the unborn baby, offered his mother a drink, which he had blended a whole bottle of abortion pills into, and she explained that she couldn't take alcohol while pregnant, Stuart offered to drink it for her. He also tried to stop Kenny when he tried to plunge the baby out of his wife and at the end is the one to suggest they name the baby Kenny.
In the episode "Mysterion Rises" it is revealed that Stuart and his wife had been part of a cult centered around Cthulhu ten years before the series' events and that he had been with Mrs. McCormick at the time. He and his wife claim to have been extremely drunk while there - something their son does not question. It is also revealed that Kenny, disguised as Mysterion, has been scaring Stuart and Mrs. McCormick not to get high at night, fight as much, and to pay their children allowances.
Stuart and his family live in a run down old bungalow. In "Chickenpox", it is revealed the house was made by Stuart and Gerald Broflovski when they were young. Their car is dismantled in front the home and is home to stray cats and dogs. Inside it is dirty and stained. The McCormicks do not own much modern technology, as the family video game system is a ColecoVision, which is plugged into a monochrome television. In "Cartman Joins NAMBLA", the North Park Funland commercial is shown in color, implying that somewhere between the episodes "Chickenpox" and "Cartman Joins NAMBLA", the McCormicks procured a color television. In "A Ladder to Heaven", they somehow managed to afford a Robot Security Guard to protect Kenny's cremated body. In "The City Part of Town", the house was upgraded on the exterior, and he does seem to care about his house, as he got pissed off at Randy and told him "I don't want you touching my damn house!"
In "Chickenpox", it is also mentioned that Stuart used to work in a pizza factory when he was a teenager. He is currently jobless, due in major part to his alcoholism, and he and his family are on welfare, and live mainly off of plain frozen waffles, pop tarts and bread sandwiches because of this. However, in "The Poor Kid" it is proved the McCormick's run a Meth lab. In "Lil' Crime Stoppers", It was stated by the Bar owners that the McCormick's make Meth for them.
It was presumed this was Kenny's father's first appearance in the Season One episode, "Death". During the commentary on this episode, creators Trey Parker and Matt Stone deny it was Stuart McCormick and claim it was another non related McCormick due his not wearing the signature red "Scotch" cap and having dark brown hair and a goatee mustache.Stuart wears a greasy, faded jean jacket overtop of a white shirt, and mucky blue jeans. He also wears a red cap, with a yellow sign featuring the word "Scotch" embroidered on the front. His hair, mustache, and beard are all a mousy-brown color. In "South Park is Gay!", he is seen wearing a bandana without his hat, a fancy sleeveless shirt, white cowboy shoes, and blue pants. After Season Thirteen, his character design model was re-polished, like many other characters. When sleeping he wears dark blue pajamas.
Stuart's surname suggests Irish and/or Scottish ancestry.
She is Stuart's wife and mother of Kevin, Kenny, and Karen. Little is known of their past, but they have been together for at least ten years, likely as old as their elder son, and share a love of drinking and drugs. Stuart is shown to care deeply for his wife, when he is sober. When drunk, he and his wife frequently argue and get into domestic squabbles, although it seems to be reinforced that they do care about each other, particularly in "Cartman Joins NAMBLA". He does seem to worry about in. In "Insecurity", he mentions "If you found out my wife was having sex with the UPS man, I'd want to you tell me".
Kevin is Stuart's elder son. He appears to be as old as Shelly Marsh, therefore being around thirteen years old. His relationship with Kevin tends to be strained, enough so that during a drunken fight with Kevin, both he and his wife are arrested.
Kenny is Stuart's younger son. Stuart is shown to care for Kenny, as he plays catch with him in "Cartman Joins NAMBLA". In South Park: Bigger, Longer & Uncut, when the army is shown singing, Stuart has a picture of Kenny on his helmet. In "I Should Have Never Gone Ziplining", Stuart was seen to be shocked and mortified at Kenny's deceased remains, which further reinforces his love and care for his son. In 'Cripple Fight', he also gets shocked when nude pictures on Kenny were shown on television, which were taken by the Scout Leader.
Karen was seen with the McCormick's in the hospital in "Best Friends Forever", she had no speaking lines. She made a second appearance in "The Poor Kid". Her name was confirmed by Matt Stone. Stuart's relationship with Karen has not been expanded on so it is unclear how he views her as a father.
In "Fat Camp", while performing on the "Krazy Kenny Show", Kenny gave his grandfather a Swedish massage. The old man's name was not given, so it is unclear whether he is Stuart's father or father-in-law.
Stuart frequently hangs out with the other local men at the bar. Being the father of one of the main characters, he is closest to Randy Marsh, Gerald Broflovski, and Stephen Stotch. Although he is not as relevant as the other fathers.
Mentioned in 'Cripple Fight', it was said that Stuart and Randy used to go to Boy Scouts when they were younger. Randy and Stuart are seen mostly in the pub together, and they seem to tolerate each other. In 'The City Part of Town', he gets angry at Randy for insulting him, saying how his house 'sucks'.
Stuart and Gerald used to be best friends in high school, until Gerald started to get better grades, while Stuart's grades declined.
In "Chickenpox", Sheila and Mrs. McCormick arranged a fishing date for their husbands, in hopes that the old friendship could be restored. The outing went awry when the two of them argued over their views on each other which eventually turned into a fist fight. They made up at the end of the episode.
Mr. McCormick: (talking to Cartman dressed as a cop) It's just me and my wife and my brother. And my wife's cousin and his son and my brother's girlfriend, and our two kids. And my brother's girlfriend's mother, and this guy Bob who I met last year.
Cartman: (to the camera) Poor people tend to live in clusters.
Mr. McCormick: What? What did you say?
- "Starvin' Marvin" - He and his wife cheer Kenny on while he's fishing for a can of preserved food.
- "Chickenlover" - Stuart and his wife are shown fighting when Cartman, as a police officer, investigates on them.
- "Chickenpox" - Stuart and Gerald go on a fishing trip in an effort to restore their old friendship.
- "The Red Badge of Gayness - Stuart participates in the war re-enactment.
- "Quintuplets 2000" - Seen at the Marsh Residence, in the audience of the Cirque du Cheville show, and on the television asking the Romanians to let Kenny come back home.
- "Cartman Joins NAMBLA" - Stuart and his wife are trying to have another baby.
- "Fat Camp" - Stuart and his wife are proud that Kenny has his own live TV show.
- "The Wacky Molestation Adventure" Stuart is taken to jail with the other parents and then returns back.
- "Cripple Fight" - Stuart does not want Big Gay Al leading the boy scouts.
- "Cartmanland" - Stuart and his wife sue Cartman because Kenny died on one of the rides in his amusement park.
- "How to Eat with Your Butt" - Stuart and his wife get Kenny to apologize to the Thompsons, when he unintentionally tricked them into thinking that their lost son had been discovered.
- "Kenny Dies" - Stuart, his wife, and family mourn Kenny's semi-permanent death.
- "Red Hot Catholic Love" - Stuart becomes temporarily atheist.
- "A Ladder to Heaven"
- "I'm a Little Bit Country" - Stuart is a pro-war fighter.
- "South Park is Gay!" - He becomes metrosexual along with all the other men.
- "Best Friends Forever" Shown beside Kenny.
- "Le Petit Tourette"- Seen at Whistlin' Willy's.
- "More Crap" - Stuart is one of the men marveling at the size of Randy's latest crap.
- "The List" - Seen eating dinner with his family and shocked after seeing Kenny getting hit by Bebe's stray bullet.
- "It's a Jersey Thing" - With Randy Marsh and the boys fight against the Jerseyites trying to take over South Park.
- "Coon 2: Hindsight" - Awakened by the Coon alarm.
- "Mysterion Rises" - Mysterion speaks with him and his wife.
- "Coon vs. Coon & Friends"
- "The Poor Kid" - Gets arrested, along with his wife.
- "I Should Have Never Gone Ziplining" - Seen shocked after receiving his son Kenny's remains from Mr. Hankey.
- "Sarcastaball" - Seen at the PTA meeting with all the other parents.
- "Insecurity" - Seen with the other adult males rallying to get rid of the UPS delivery driver.
- "A Scause For Applause" - Seen in the background while Jesus Christ gives his speech.
- "Informative Murder Porn" - Complains to the local cable company after his murder porn television programming is blocked and learns to play MINECRAFT.
- "A Song of Ass and Fire" - Comments on Kenny's princess outfit.
- "Handicar" - He watches Wacky Races in his pajamas while eating cereal.
- "The Magic Bush"- Seen at the neighbourhood watch meeting.
- "Cock Magic" - He is confronted by the police, who ask him about an illegal cock magic ring, which he has no knowledge of.
- "Stunning and Brave"
- "The City Part of Town" - Stuart is enraged of the newly built SoDoSoPa all around his house to make that part of town appear more cultural.
- "Naughty Ninjas"- Trying to call the police after homeless are living outside his house.
- "Skank Hunt" - Seen at the school assembly.
- Stuart's favorite liquor seems to be scotch, as it is written on the front of his trademark cap. This is also referenced by Eric Cartman in "Pinkeye".
- In "The Red Badge of Gayness", it is noted that Stuart is employed, although this may be false since this is never brought up again.
- A character referred to as 'Mr. McCormick' kills himself in the episode "Death". The character is similar to Stuart in many respects.
- Stuart is apparently very skilled in architecture, construction, and electronics. He and Gerald Broflovski built a clubhouse in their earlier years, which became the house the McCormicks now live in.
- Stuart can be found in South Park: The Stick of Truth outside Skeeter's Bar and Cocktails. You have to destroy some trash to wake him up, and then you can walk over to him and get a friend request.
- As of Season Seventeen, Stuart has had a speaking role in 26 episodes.