Brawl in Cell Block 99 is a 2017 American neo-noir prison action thriller film directed and written by S. Craig Zahler and starring Vince Vaughn with Jennifer Carpenter, Don Johnson, Udo Kier, Marc Blucas, and Tom Guiry. The story follows Bradley Thomas, a drug mule who must kill a man held in a maximum security prison to rescue his pregnant wife from a vengeful drug lord.

Zahler wrote the script of Brawl in Cell Block 99 after watching several prison films, coming up with different elements to add to the genre. He cast Vaughn for his consistency and authenticity, in a break from the comedic roles that Vaughn usually plays. Vaughn exercised and underwent training for the film's action and fighting sequences. Filming took place in Staten Island, New York City, between August and October 2016 under a production budget of $4 million.

The film premiered at the 74th Venice International Film Festival, and was released in theaters, digital HD, and video on demand in October 2017, by RLJE Films. It received mainly positive reviews which praised Vaughn's performance and the film's 1970s exploitation style. The film was named among the year's best films by the Los Angeles Times, The New York Times, and The A.V. Club.