What to Watch on HBO Max in September 2026

Head into the 'Backrooms,' and once you escape, check out all the other cool stuff on the streamer this month. 2026 has been a landmark year for horror movies, and this month HBO Max lands one of the biggest of them all, Backrooms , thanks to its partnership with A24. If you're not looking to be scared, the rest of September's programming is equally strong, including …