BAC Nord (internationally titled The Stronghold) is a 2021 French action thriller film co-written and directed by Cédric Jimenez from a screenplay by Jimenez and Audrey Diwan, starring Gilles Lellouche, François Civil, Karim Leklou, Adèle Exarchopoulos, and Kenza Fortas. The film made its world premiere at the 2021 Cannes Film Festival out of competition on 12 July 2021. StudioCanal released the film theatrically in France on 18 August 2021. The film received seven nominations for the 47th César Awards, including Best Film, Best Director, Best Actor and Best Supporting Actor.

The plot is based on a scandal that took place in 2012 within the anti-crime brigade (French: fr:brigade anticriminalité, BAC) of Marseille where eighteen members were indicted for drug trafficking and racketeering.