A hollowed asteroid is a hypothetical space habitat in which an asteroid has been hollowed, creating a living space within the center cavity or cavern network. Pressurized gases, usually a mixture of oxygen, nitrogen, and carbon dioxide, can be trapped within the confines of the rock, allowing for a breathable atmosphere. In some worldbuilding examples of this element, the asteroid has been given a rotational spin, generating a force approximating Earth’s gravitational pull on those residing within the interior of the asteroid.

For worldbuilders including hollowed asteroids in their worlds, consider the size of the celestial body, what types of rock, metals, and ice the asteroid is composed of, and the reasons for why a group may want to make it a home or base.