The class 9 torpedo was a type of photon torpedo used by Intrepid-class starships.
USS Voyager had a number of class 9 torpedoes in its weapons manifest in 2375. After the ship was consumed by a bioplasmic organism, colloquially known as a "telepathic pitcher plant", Qatai thought that "if we can bring [Voyager] deeper into the creature's digestive tract and detonate one of these charges, we might be able to destroy it." (VOY: "Bliss")