The Big Bang Theory is an American television sitcom created by Chuck Lorre and Bill Prady for CBS. It aired from September 24, 2007, to May 16, 2019, running for 12 seasons and 279 episodes.

The show originally centered on five characters living in Pasadena, California: Leonard Hofstadter (Johnny Galecki) and Sheldon Cooper (Jim Parsons), both physicists at Caltech, who share an apartment; Penny (Kaley Cuoco), a waitress and aspiring actress who lives across the hall; and Leonard and Sheldon's similarly geeky and socially awkward friends and coworkers, aerospace engineer Howard Wolowitz (Simon Helberg) and astrophysicist Raj Koothrappali (Kunal Nayyar). Over time, supporting characters were promoted to starring roles, including neuroscientist Amy Farrah Fowler (Mayim Bialik), microbiologist Bernadette Rostenkowski (Melissa Rauch), and comic book store owner Stuart Bloom (Kevin Sussman).

The show was filmed in front of a live audience and produced by Chuck Lorre Productions, with Warner Bros. Television handling distribution. It received mixed reviews throughout its first season, but reception was more favorable in the second and third seasons. Despite early mixed reviews, seven seasons were ranked within the top ten of the final season ratings, and it ultimately reached the No. 1 spot in its eleventh season. It was nominated for the Emmy Award for Outstanding Comedy Series from 2011 to 2014 and won the Emmy Award for Outstanding Lead Actor in a Comedy Series four times for Parsons, totaling seven Emmy Awards from 46 nominations. Parsons also won the Golden Globe for Best Actor in a Television Comedy Series in 2011.

The series' success launched a multimedia franchise. A prequel series based on Parsons' character Sheldon Cooper, Young Sheldon, aired from 2017 to 2024, with Parsons as the narrating adult Sheldon. The third series in the franchise, a sequel series to Young Sheldon titled Georgie & Mandy's First Marriage, premiered in October 2024 and follows Sheldon's older brother, Georgie, and his wife, Mandy. A fourth series, following Stuart, his girlfriend Denise, and geologist Bert Kibbler, is in development for Max.