Louis has appeared several times throughout South Park as a background, or filler, character. His first appearance was in "Tweek vs. Craig" as one of the students viewing the fight between Tweek and Craig.
Louis also made an appearance in "Super Fun Time" as a member of the Boys' class on a field trip to the Pioneer Village. In "Chinpokomon", he received his first speaking role, and he later received his second speaking role twelve years later in "Funnybot", when he screams, "It's the Germans!" His religion is revealed to be Jewish in "Jewbilee".
Louis wears black shoes, gray pants, a dark blue coat, and a red scarf with black stripes. He has brown hair.
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- "Tweek vs. Craig" - He is shown watching the fight.
- "Jewbilee" - Becomes a Jew Scout.
- "South Park: Bigger, Longer & Uncut" - Seen in the movie theater seeing the Terrance and Phillip movie.
- "Chinpokomon" - Seen fighting over a toy with Bradley Biggle.
- "Hooked on Monkey Fonics"
- "Mr. Hankey's Christmas Classics"
- "Cartman's Silly Hate Crime 2000"
- "Cartman Joins NAMBLA" - Seen with an older man.
- "Fat Camp" - Seen in the playground.
- "Casa Bonita" - He is shown walking in the hallway when Cartman beats up Jimmy.
- "Butt Out" - Seen watching the Butt Out program.
- "Raisins" - Shown eating at Raisins.
- "Stupid Spoiled Whore Video Playset" - Seen at Bebe's party.
- "The Return of Chef"
- "Le Petit Tourette"- Seen at the toy store.
- "Eek, A Penis!" - Seen in hallways; background only.
- "Super Fun Time" - He appears at Pioneer Village as a part of the field trip as Annie Faulk's partner.
- "Elementary School Musical"
- "Eat, Pray, Queef"- Briefly seen in the distance in the hallway.
- "Butters' Bottom Bitch"
- "The Tale of Scrotie McBoogerballs" - Seen on the playground.
- "Crème Fraiche" - Seen standing in line in the cafeteria.
- "Funnybot" - He screams "It's the Germans!" in the hallway.
- "Bass to Mouth" - Seen in the hallways.
- "1%" - Seen in the gym.
- "The Poor Kid" - Seen in the crowd of students in the hallway.
- "Cash For Gold" - Seen in the background on the playground.
- "Faith Hilling" - Seen exiting the school with the other children.
- "Jewpacabra" - Seen at the Easter egg hunt.
- "Butterballs" - Seen in the background in the cafeteria and in the hallways.
- "Cartman Finds Love" - Seen in the background in the school's hallways.
- "Sarcastaball" - Seen in the background in the locker room.
- "A Scause For Applause" - Seen in the background in the school hallways talking to Jason.
- "Informative Murder Porn" - Seen in a town meeting at the Community Center.
- "Gluten Free Ebola"- Seen at the boys party.
- "The Cissy"- Briefly seen in the school hallway.
- "Stunning and Brave"
- "Sponsored Content"- Seen in the hallway.
- "PC Principal Final Justice"- Seen in the school assembly.
- "Member Berries"- Seen at the school assembly.
- "Skank Hunt" - Seen in the school cafeteria and his girlfriend breaks up with him.
- "The Damned" - Seen on social media in the school hallway.
- "Wieners Out" - Seen participating in Butters' Wieners Out movement.
- "Douche and a Danish" - Seen in the battle between the boys and the girls.
- "Oh, Jeez" - Seen at the school assembly.
- "Hummels & Heroin" - Seen at Marcus' birthday party.
- "SUPER HARD PCness" - Seen in the hallway evacuating to the gym.
- "The Problem with a Poo" - Seen in the school assembly.
- "The Scoots" - Seen at Halloween Outlet.
- "Buddha Box" - Seen at the restaurant.
- "Bike Parade" - Seen at the bike parade.
- "Band in China" - Seen at the Autumn Fest.
- "Shots!!!" - Seen in the cafeteria.
- "Let Them Eat Goo" - Seen in the corridor.
- "Board Girls" - Seen at the school assembly.
- "Basic Cable" - Seen in the school bus.
- Before his name was a revealed, he was known as "Tripply" or "Scarf Boy".