Her name is revealed in "The Pandemic Special" when she appears with other parents on a Zoom conference with Mr. Mackey about allowing their children to return to school. When the students are quarantined in school for two weeks, she is revealed to be Red's mother when Red is seen on a Zoom call with her parents in the computer lab. Mr. McArthur tells Red that they miss her.
Moira McArthur has shoulder-length red hair with a center parting and long eyelashes. She wears a gray cardigan over an olive green shirt, either a black knee-length skirt or dark blue pants, and black shoes.
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- "Pandemic" - Seen on the news during the first attack of the guinea creatures.
- "About Last Night..."
- "The Tale of Scrotie McBoogerballs" - Seen reading Butters' new book.
- "200" - Seen at the town meeting about Muhammad.
- "Broadway Bro Down"
- "Cartman Finds Love" - Seen in the audience of people awing over Cartman's song to Kyle.
- "Sarcastaball" - Seen at the Sarcastaball PTA meeting, the rally at the park, and watches the boys' Sarcastaball match while holding a bottle of Butters' Creamy Goo.
- "Raising the Bar"
- "A Scause For Applause"
- "A Song of Ass and Fire" - Looks at Princess Kenny as she walks along the street.
- "Gluten Free Ebola" - Seen at the Park County Community Center.
- "Handicar" - Seen leaving the theater.
- "Naughty Ninjas" - Seen protesting outside Park County Police Station.
- "Sponsored Content" - A dark-haired version of Moira is seen in the audience of the 2015 Presidential debates.
- "PC Principal Final Justice" - Seen at The South Park Gun Show.
- "Skank Hunt" - A dark-haired version of Moira is seen at the PTA meeting.
- "Douche and a Danish"
- "Franchise Prequel"
- "Splatty Tomato"
- "A Boy And A Priest"
- "The Scoots" - Seen at the beginning of the episode decorating a blue house and is later seen at the Park County Community Center.
- "Nobody Got Cereal?"
- "Bike Parade"
- "Let Them Eat Goo" - Seen at the announcement for Tegridy Burger.
- "Board Girls"
- "Christmas Snow"
- "The Pandemic Special" - Appears in a Zoom conference with Mr. Mackey and other parents. Later she and her husband have a Zoom call with their daughter.
- "South ParQ Vaccination Special" - Seen waiting in line outside Walgreens to get a COVID-19 vaccine.