A subspace shock wave is a violent release of energy which travels at faster-than-light velocities, and which can be created by the destruction of large stellar bodies, such as a planet or a star.

In 2293, the destruction of the Klingon moon Praxis produced a subspace shock wave which caused severe damage to the Klingon homeworld's atmosphere, as well as the nearby USS Excelsior. (Star Trek VI: The Undiscovered Country; VOY: "Flashback")

In 2372, Kira Nerys and Miles O'Brien detected elevated tachyon readings and subspace shock waves, created as byproducts of a cloaked Klingon ship exploding after having collided with a cloaked mine just outside of Bajoran space. (DS9: "Sons of Mogh")

In 2373, several subspace shock waves were generated as byproducts of the supernovae created by the civil war in the Q Continuum. These shock waves collapsed the USS Voyager's warp field, making it impossible for them to escape. (VOY: "The Q and the Grey")