Bill or Billy may refer to a number of characters and celebrities featured on South Park.
- Bill Allen - A background character usually seen with Fosse McDonald, especially in earlier seasons.
- Bill Cosby (BSM-471) - A cyborg from the future seen in "Trapper Keeper".
- Bill Denkins - The recurring farmer from the first Seasons, who lives near South Park.
- Bill Keegan - The latest news anchor for the Channel 4 Evening News.
- Bill Stewart - An elderly man who tries to take over South Park in "Grey Dawn".
- Billy Martin - A background South Park Elementary student.
- Billy Miller - A KFC smuggler featured in "Medicinal Fried Chicken".
- Billy Circlovich - A boy featured in "The Tooth Fairy Tats 2000".
- Billy Thompson - A boy who bullied Mr. Mackey when he was in school, seen in "Insheeption".
- Billy Turner - A boy mentioned in "Tsst" as having been forced to self-mutilate by Cartman to survive.
- Billy (Kindergartner) - A recurring first grade school children.
- Billy Harris - A first grade school children who appeared in "Trapper Keeper".
- Billy ("Sons A Witches") - A boy featured in "Sons A Witches".
- Billy Bob Thornton - Actor and musician who appeared in "Sexual Healing".
- Billy Mays - The famous loud advertising spokesman seen in "Dead Celebrities".
- Bill Clinton - Former President of the United States, featured in South Park: Bigger, Longer & Uncut.
- Bill Cosby - A rich African-American entertainer who comes to the town in "Here Comes the Neighborhood".
- Bill Donohue - A member of the Catholic church who attempts to become Pope in "Fantastic Easter Special".
- Bill Gates - Founder and former CEO of Microsoft, seen in "South Park: Bigger, Longer & Uncut" and "A Song of Ass and Fire".
- Bill O'Reilly - A political commentator and host of The O'Reilly Factor, featured in "Goobacks".
- Bill Owens - Former Governor of Colorado.