The 4th Grade is the class grade most characters are in since "Fourth Grade". It encompasses most child characters, although there is likely another 4th Grade classroom as many characters do not appear in the main classroom.
- Ms. Choksondik - The main Fourth Grade Teacher from "Fourth Grade" to "Professor Chaos".
- Mr. Mackey - Covered after Ms. Choksondik's death, also teaching computer class and drug lessons.
- Herbert Garrison - 3rd grade teacher from "Cartman Gets an Anal Probe" to "Cartman Joins NAMBLA". Returned to the school as a kindergarten teacher in "Trapper Keeper". He was rehired as a 4th grade teacher in "The Death Camp of Tolerance" and was fired from the entire school in "Where My Country Gone?" for calling his Canadian students "Canucks" and interrupting the Canadian history assembly only so he could insult the Canadians.
- Mrs. Nelson- Mr. Garrison's replacement after he was fired for interrupting the Canadian history assembly. So far she has only appeared once teaching the class about planets briefly during the Whole Foods Inspection.
- Mr. Slave - Mr. Garrison's teaching assistant From "The Death Camp of Tolerance" to "Fat Butt and Pancake Head " and "South Park is Gay!". He was part of Mr Garrisons get rich quick plan, which backfired and ended with a forced stay at the Tolerance Camp for a week.
- Mrs. Dreibel - Teaches art in her own classroom during "Toilet Paper"
- Richard Dawkins - Teaches evolutionary studies.
- Mr. Adler - He is the teacher in Shop Class.
- Pearl - She teaches Home Economics.
Students in this section are seen in Mr. Garrison's fourth grade classroom in almost all episodes.
- Annie Knitts
- Bebe Stevens
- Butters Stotch
- Clyde Donovan
- Craig Tucker
- Eric Cartman
- Jimmy Valmer ("D-Yikes!" onward)
- Kenny McCormick
- Kyle Broflovski
- Stan Marsh
- Timmy Burch
- Token Black
- Wendy Testaburger
Students in this section are seen in Mr. Garrison's fourth grade classroom but only in some episodes.
- Boy with Red Shirt and Blue Pants
- Bradley Biggle
- Heidi Turner
- Jason White
- Kevin Stoley
- Millie Larsen
- Peter Mullen
- Sally Turner
- Tweek Tweak (regular until "Elementary School Musical")
Other 4th Graders
- See also: The Other 4th Grade
Students who have not been seen in Mr. Garrison's fourth grade class but are fourth graders.
- Brimmy (was in Third Grade class)
- Damien Thorn (was in Third Grade class)
- DogPoo Petuski (was in Third Grade class)
- Mark Cotswolds (were in Third Grade class)
- Terrance Mephesto (was in Third Grade class)
- Bill Allen (was in Third Grade class)
- Fosse McDonald (was in Third Grade class)
- Tommy Turner
- Allie Nelson (replaced Pip after his death)
Students who used to appear, but have since vanished without explanation, moved away, or died.