Ghost

"In its dying breath, The Traveler created the Ghosts to seek out those who can wield its Light as a weapon—Guardians—to protect us and do what the Traveler itself no longer can."

- The Speaker, Destiny, Restoration

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 locates 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.

Trivia

 * In Destiny, players can find dead Ghosts scattered around the game. Reviving them unlocks Grimoire cards.
 * Peter Dinklage originally provided the voice of the Ghost. Nolan North replaced Peter Dinklage as the voice of the Ghost in Destiny: The Taken King.
 * An advertisement for Destiny claimed that Ghosts existed during the Golden Age. This is most likely an error, as all other sources available have stated that the Ghosts were created by the Traveler after the Golden Age ended.
 * Holding a Ghost near a normally un-openable door will cause it to open, revealing a cloud of darkness behind it.
 * Introduced in Destiny: The Taken King, when the Ghost Icon appears in the right corner of the screen, the Ghost will look towards/guide their Guardian (when they are held on-screen) to items that need investigation. This feature is also available in Destiny: Rise of Iron and Destiny 2.