The Phantom Crushers are elite soldiers of the Downfall organization possessing the power to remove someone's Hazard Level and antagonists in movie Kamen Rider Build NEW WORLD: Kamen Rider Grease.
During Downfall's attack on the Japanese government, Simon Marcus transformed into a Phantom Crusher to defeat Kamen Rider Rogue and disable his ability to transform. Phantom Crushers were then sent to eliminate the other Kamen Riders. A Phantom Crusher succeeded in disabling Sento Kiryu and Ryuga Banjou's abilities to transform and stole the White Pandora Panel, but another could not disable Kazumi Sawatari or the Hokuto Three Crows' transformation abilities and was forced to retreat after being overwhelmed by their power.
Phantom Crushers later participated in Downfall's assault on Japan's streets, only to be stopped and defeated by the Kamen Riders after they regained their ability to transform from a Nebula Gas elixir.