Tammy Nelson is a background character. She is often seen in the corridors in South Park Elementary. Her first speaking role was in "Bass to Mouth", where she admitted to Emily Anderson that her mother was an alcoholic. Her name was confirmed in "Bass to Mouth". She is not to be confused with Tammy Warner, Kenny's one time girlfriend in The Ring.
Tammy wears a light-purple jacket and dark-purple pants along with a purple hair tie.
It was seen in "Bass to Mouth" that her and Emily are very close friends, probably best friends, considering they both admitted and comforted each other over their mothers being addicts/alcoholics (an extremely personal matter).
- "Quest for Ratings" - Seen at Middle Park Elementary.
- "Le Petit Tourette"
- "Tonsil Trouble" - Seen watching Kyle Broflovski and Eric Cartman's fight in the playground.
- "Breast Cancer Show Ever"
- "Butters' Bottom Bitch"
- "Bass to Mouth" - Speaks to Emily Anderson about her mother's alcoholism.
- "Jewpacabra" - Seen at the Easter egg hunt.
- "Let Go, Let Gov" - Seen in the school hallways talking to Nelly and Emily Anderson.
- "Stunning and Brave"- Seen in the hallway.
- Tammy shares her last name with another student at South Park Elementary, Patty Nelson. They may be related.