Marrow Deep is the ninth studio album by the American heavy metal band Mastodon. It was released on August 28, 2026, by Loma Vista Recordings, the band's first release on the label. Produced by Patrik Berger and Kurt Ballou, it is Mastodon's first album with guitarist Nick Johnston, following the departure and subsequent death of founding lead guitarist Brent Hinds in 2025, and the first with keyboardist João Nogueira as an official member. It is also Mastodon's first album as a five-piece band.