Onyx Cave

Onyx Cave may refer to several things in the United States:


 * Onyx Cave (Arizona), a National Natural Landmark
 * Onyx Cave (Arkansas), a small show cave
 * Onyx Cave (Kentucky), a show cave
 * Great Onyx Cave, Kentucky
 * Great Onyx Cave Entrance, Mammoth Cave, Kentucky, listed on the NRHP in Kentucky
 * Crystal Onyx Cave, Kentucky
 * Onyx Cave (Newburg, Missouri), listed on the NRHP in Missouri
 * Onyx Mountain Caverns, Missouri