A Ghost is a levitating artificial intelligence used by Guardians. Ghosts support Guardians by performing certain actions such as illuminating darkened areas, hacking Golden Age technology, and informing Guardians of incoming hostile threats. Ghosts also have a navigation mode which locate mission objectives and Faction missions from the Tower.

Ghosts originated from The Traveler's technology and Light and seek out their Guardian companions from the ancient dead, reviving them, and afterwards, resurrecting them continuously if they are killed by the forces of The Darkness.