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 (Cory Monteith), and who teams with fellow athlete and bully Azimio (James Earl) to torment various fellow students, usually members of the school glee club, New Directions.

Karofsky was initially used as an ordinary jock bully, but Adler's acting impressed show co-creator Ryan Murphy; he expanded Karofsky's role in the show's second season by having him especially target gay glee club member Kurt Hummel (Chris Colfer), only to turn out to be gay himself, though closeted.

That revelation sparked a wave of reaction from people who thought it was important for Glee to show "the confusion and the torture one person can put themselves through being closeted".

[1] Reviewers have been impressed with Adler's portrayal of Karofsky, including Michael Slezak of TVLine, who in the second season characterized it as "surprisingly nuanced" and with a "terrific amount of depth", and Billboard's Rae Votta, who wrote in the third season, "As always, Kurt and Karofsky's scenes shine as the strongest in whichever episode they're featured.

He reappears in "Mattress", teamed with football player Azimio (James Earl) and writes on Finn's face with black markers to demonstrate how they will deface the glee club's yearbook photo, which Karofsky does at the end of the episode.

By "Theatricality" he is on the football team with Azimio and they shove Kurt Hummel (Chris Colfer) and Tina Cohen-Chang (Jenna Ushkowitz) against lockers for wearing Lady Gaga costumes—part of a glee club assignment—around school.

Karofsky joins in when he sees the crowd's positive reaction to the start of the half-time show, a mashup of "Thriller" and "Heads Will Roll"; the full team ultimately wins the game.

Karofsky apologizes to Kurt for his bullying in a meeting with Will, Principal Figgins (Iqbal Theba) and their respective fathers Paul (Daniel Roebuck) and Burt.

In "On My Way", he is taunted and bullied by his athletic teammates and by others at school and using online media, so severely that he attempts to hang himself, but is saved by his father in time.

Dave Karofsky is played by actor Max Adler, who first appeared in the first season episode "Mash-Up", initially as a member of the William McKinley High School hockey team.

[16] Although Karofsky begins the second season as an ordinary jock bully, Murphy hinted to Adler that there would be more in store for the character.

"[18] Murphy has indicated a preference for positive future developments, and said in early January 2011, "This show is by nature optimistic and I think a character like Karofsky could turn to booze or pills or alcohol and kill themselves or do something dark.

"[21] MTV's Aly Semigran wrote that, should the episode inspire a single teenager to have courage in the face of discrimination, or re-consider bullying, it would be an impressive accomplishment.

[23] His appearances over the next few episodes drew only oblique commentary, such as The Atlantic's Kevin Fallon's characterization in his review on "Furt" of the bullying storyline as a "very important arc that's been well-acted by all parties involved".

Club's Emily VanDerWerff wrote, "I thought giving Kurt's bully, Karofsky (...), a miniature story arc that resolved itself only partially was a smart move.

Michael Slezak of TVLine complimented "Max Adler's surprisingly nuanced performance" as Karofsky in "Born This Way": "The complex play of emotions in Karofsky's eyes when Santana simultaneously came out to him, threatened to out him, predicted his sad future as a closeted state senator or deacon, and offered him a quick-fix solution by pretending to be his beard, was tremendous.

"[2] VanDerWerff referred to Karofsky's parallel journey with Santana, who is also closeted, in her comments about the episode and the next one where the character appears, "Prom Queen".

[28] Meghan Brown of The Atlantic praised Karofsky's "tearful apology to Kurt" in that episode as being "painful and poignant",[29] and Slezak went further: Whatever awards Chris Colfer and Max Adler get nominated for in the next six months, they earned 'em during this conversation, where Kurt wondered if maybe, just maybe, he wasn't getting bullied because kids were indifferent to him being gay, not because Karofsky was serving as his security detail.

... [Y]ou could see in Kurt's eyes the decision to start treating Karofsky not as a former tormentor, but as a terrified kid struggling with his sexual orientation.

[37] VanDerWerff wrote, "The sequence in which Karofsky prepared himself for death was, unquestionably, one of the best things Glee has ever done", and Slezak called it "as devastating as anything I’ve seen on TV this year".

[41] Rae Votta of Billboard wrote, "As always, Kurt and Karofsky's scenes shine as the strongest in whichever episode they're featured.