The Ninukab is member of a ghostly group of aliens from an extinct world. These entities inhabit buildings (and other artificial structures throughout the universe) that contain living spirit to sustain them. One Ninukab inhabits the body of Peter Demeos, as well as the skyscraper that he built. It fights both Demeos and Superman in an attempt to go on living in its adopted building home. When the skyscaper is destroyed, the spirit leaves to find another home somewhere in the galaxy (S No. 262, Mar 1973: "The Skyscraper that Screamed for its Life!").