David Karofsky is a recurring fictional character from the Fox musical comedy-drama series Glee. The character is portrayed by actor Max Adler, and has appeared in Glee since its first season episode "Mash-Up", first broadcast on October 21, 2009. Initially known only by his surname, Karofsky was introduced as a bully and a member of the McKinley High football team who slushies football captain Finn, and who teams with fellow athlete and bully Azimio to torment various fellow students, usually members of the school glee club, New Directions. Later in the season, he is identified as a member of the football team, and is a football player in the second season. Karofsky is revealed to be gay early in that season. He is closeted and remains so at the end of the season, though he has stopped bullying and has won the election for Junior Prom King. He transfers to another school for his senior year, but is outed there and attempts suicide after being bullied by his classmates, though he is saved by his father.

"Mash-Up" is the eighth episode of the American television series Glee. The episode premiered on the Fox network on October 21, 2009. It was written by series co-creator Ian Brennan and directed by Elodie Keene. The episode sees glee club director Will Schuester attempt to create a wedding medley in the style of a mash-up for his colleagues Emma and Ken. Students Finn and Quinn find that they are no longer considered popular, while glee club members Rachel and Puck become romantically involved, as do cheerleading coach Sue Sylvester and local news anchor Rod Remington.