Peter Nelson made his first appearance in "Make Love, Not Warcraft".He is a co-worker and friend of Randy Marsh at the South Park Geology office. Nelson is also a member of the Cult of Cthulhu, and the Hare Club for Men. In "Broadway Bro Down", he is revealed to have a wife.
Nelson has long gray hair and glasses. He wears a green shirt, pocket protector, and brown pants. He usually wears a green shirt except when he is attending a Cthulhu cult ritual, then he has a black robe.
Nelson seems rather calm and uninterested in whatever is going on. When Randy was showing off his avatar in World of Warcraft, he casually remarked on how it was killed easily by the griefer. Even when he is interested he still acts very passive about it such as football, marijuana and blow-jobs from his wife.
- Randy has had several co-workers named Nelson; in "Goobacks," Randy is fired by a Mr. Nelson. In "Bloody Mary", an off-screen Nelson from work says goodbye to Randy.
- The Broadway Musical he took his wife to was called Wicked.
- "Make Love, Not Warcraft" - He is seen as a co-worker looking at Randy's World of Warcraft game.
- "Fantastic Easter Special" - He is captured by Bill Donohue and is seen in a bunny costume.
- "Over Logging" - Randy tells Sharon he needs to send an email to Nelson before going to bed (mentioned only).
- "Medicinal Fried Chicken" - He and many others purposely gave themselves testicular cancer so they could buy marijuana legally.
- "Mysterion Rises" - Nelson is revealed as a member of "The Cult of Cthulhu."
- "Broadway Bro Down" - Tells Randy about taking his wife to Broadway musicals to get blow-jobs.
- "Reverse Cowgirl" - Randy mentions that he and Nelson make X's with their pee on sleepover nights (mentioned only).
- "The Cissy" - He is questioned about the identity of Lorde by SPIN reporter Brandon Carlile.
- "The Magic Bush" - Seen being spied on by Randy while having sex with his wife.
- "PC Principal Final Justice" - Seen in the crowd of people standing in front of the Whole Foods Market.
- "The Damned" - Seen briefly at Skeeter's Wine Bar.
- "Holiday Special" - Seen helping Randy pull down a Columbus Statue.