Which American TV show takes place in Sunnydale?

"Buffy the Vampire Slayer" is an American supernatural drama television series based on the 1992 film of the same name. It was created by Joss Whedon under his production tag, Mutant Enemy Productions, with later co-executive producers being Jane Espenson, David Fury, David Greenwalt, Doug Petrie, Marti Noxon, and David Solomon.

The show is set in the fictional California town of Sunnydale, whose suburban Sunnydale High School sits on top of a "Hellmouth", a gateway to demon realms. The Hellmouth, located beneath the school library, is a source of mystical energies as well as a nexus for a wide variety of evil creatures and supernatural phenomena. In addition to being an open-ended plot device, Joss Whedon has cited the Hellmouth and "High school as Hell" as one of the primary metaphors in creating the series.