Extraterrestrial real estate refers to claims of land ownership on other planets, natural satellites, or parts of space by certain organizations or individuals. Previous claims are not recognized by any authority, and have no legal standing. Nevertheless, some private individuals and organizations have claimed ownership of celestial bodies, such as the Moon, and are actively involved in "selling" parts of them through certificates of ownership termed "Lunar deeds", "Martian deeds" or similar.

The International Star Registry (ISR) is an organization founded in 1979 for the purpose of giving the general public the novelty of unofficially naming stars.