William “Billy” Sparks was a neighbor of Sheldon, who claimed on The Big Bang Theory that he was one of his childhood bullies. He was mentioned being on Sheldon's all-time enemies list in "The Creepy Candy Coating Corollary" and “The Shiny Trinket Maneuver", where Sheldon claimed he shoved a Mexican Peso up Sheldon's nose. He appears in the series spinoff "Young Sheldon".
In "Poker, Faith, and Eggs", having a crush on Missy he gifted her with a basket full of eggs. When the Cooper family cooked and ate those eggs, they became violently ill from food poisoning as it turns out those eggs were Salmonella-contaminated.
In "A Computer, a Plastic Pony, and a Case of Beer", Sheldon wrote on a TANDY 1000 SL System computer that Billy Sparks threw a chicken at him.
- Father: Herschel Sparks
- Mother: Brenda Sparks
- Sister: Bobbi Sparks
- Although Sheldon (who frequently tends to exaggerate or even outright lie about his childhood on TBBT) has claimed that Billy was one of his childhood bullies, events involving Billy that were seen in Young Sheldon appear to disprove those claims as he is most often merely seen being clueless and dimwitted, often having little idea what goes on around him most of the time. They were never friends in Young Sheldon, they don't hang out a lot because Billy hates Sheldon.
- Despite initially acting like a bully, over the course of Young Sheldon he's become more happily-dim-but-harmless, and even seems to like spending time with Sheldon on occasion. Somewhere down the line, he really hates Sheldon and they are not considered friends. Her sister Bobbi Sparks is the only who is bullying Sheldon.
- Billy might be Missy's soon to be ex-husband.
- Billy has been shown to be somewhat slow/dimwitted as evidenced by multiple scenes in the show like when his mother said that whenever his Spanish teacher would say "si" Billy would respond by saying "See what?".
|The Big Bang Theory Episodes|
|Young Sheldon Episodes|
|Appeared||M = Mentioned||Did not appear||Not aired/Not available|
|V = Voiced||C = Cameo||F = Flashback||I = Indirectly mentioned||P = Pictured|