Harry Potter

Harry Potter is a series of seven epic fantasy novels written by British author J.K Rowling, portraying the adventures of Harry Potter and his companions as they study at Hogwarts School of Witchcraft and Wizardry, and their struggle against the evil Lord Voldemort. The series has since developed into a worldwide booming franchise, containing theme parks and movies. Harry Potter isn't mentioned or referenced as much in the show as other franchises, but Sheldon and Penny have both read the books, and Leonard had already read the first five by The Spoiler Alert Segmentation.

Episodes
In the Spoiler Alert Segmentation(S06E15), Lenoard was reading Harry Potter and the Half Blood Prince when Sheldon spoilers the ending by revealing that Dumbledore died, igniting an argument between the two. As Leonard storms out, Sheldon also spoils book 7 be revealign the death of Dobby the elf to spite Leonard. Later in the episode, Penny accidently spoils that Harry Potter and Ginny Weasley become a couple to Leonard, much to his chargain.

In the First Pitch Insufficiency(S08E03), Sheldon reveals that all the guys are members of the Gryffith Park Quidditch team, a game based off the sport from the Harry Potter books.