The Traveler

The Traveler is a mysterious, city-sized sphere in Destiny and Destiny 2 that hangs low over the Earth.

History
The Traveler's origins are unknown. When it arrived, humanity first discovered it on Mars. It sparked a Golden Age of humanity that allowed humans to migrate from Earth to colonize other planets within the Solar System. Some speculate that the Traveler is a large vessel; others believe that it is a sentient being or artificial intelligence and some may even consider it a deity. As of yet its true nature is unknown.

The Traveler is credited with humanity's survival during the Collapse of the Golden Age. After the Traveler sacrificed itself to save humanity, it remained floating not far from the Earth's surface, and became silent and dormant. The Last City was built in its shadow and under its protection, where its inhabitants are temporarily safe from the threat of the Darkness.

The Red War
A year following the SIVA Crisis, Dominus Ghaul, leader of the Red Legion, attacked the City and trapped the Traveler inside a special device, cutting off its Light from the Guardians. As the Red Legion occupied the City, they began constructing a cage around the Traveler for the purpose of extracting its Light, which would allow the Cabal to gain powers akin to its Guardians. Ghaul also captured the Speaker to question him about the Traveler's Light, but the Speaker only wasted his time before ultimately admitting that the Traveler never spoke to him.

During Commander Zavala's attack to retake the City, the Guardian came face-to-face with Ghaul aboard his command ship, where he was in the process of absorbing some of the Traveler's Light. Though the Guardian managed to kill Ghaul, he was resurrected as a massive ethereal figure of pure Light. As the Red Legion leader declared his apotheosis and the dawning of a new age, the Traveler began to wake for the first time in centuries; the cage fractured and exploded as The Traveler broke free. The Traveler obliterated the cage and Dominus Ghaul, releasing a pulse of Light that reached throughout the solar system and beyond the entire galaxy.

Season of Arrivals & Beyond Light
As the Black Fleet has now returned, alerted and reawoken by the explosive pulse of Light during the Traveler's escape from the Cabal cage, all Guardians were called to convene at the City where the Traveler had begun to heal the damage to itself caused by the Red War. The Traveler appeared to regenerate itself by drawing in energy from all around it, brightening the skies as it reformed. The massive cracks in it's surface have now largely been mended, although some damage from the Collapse remains. Eris Morn commented that the Traveler healing itself would not result in the end of the conflict between itself and the Darkness "Pyramids" that have been threatening the universe; it will merely cause the conflict to escalate. With its strange healing ritual complete, the Traveler unleashed another pulse of Light to push the Darkness back, forcing a temporary stalemate. The Darkness now occupies the edges of our solar system, and multiple human colonies have fallen out of contact and in some cases, vanished altogether.

Rise of the Lucent Hive
Following Savathûn's fatal separation from her worm familiar, she translocated herself to the mountains outside the City, where she addressed the Traveler, remarking that she had chased it for a long time, first as an adversary, then as a collector and now a supplicant. Some time after she expired, for unknown reasons, the Traveler sent a Ghost to resurrect her, thus granting the Hive the Light.

The Guardian's investigations into Savathûn's throne world revealed that the Witch Queen planned to protect the Traveler by sealing it away in her throne world, threatening the Guardians' connection to the Light. Furthermore, when the Guardian discovered the Traveler's involvement with Savathûn's resurrection, the Vanguard questioned why the Traveler's motives, as Zavala furiously reminded that the Traveler once sacrificed itself to save humanity from the Darkness, including the Hive. Ikora Rey declared that regardless of the Traveler's actions, they would stop Savathûn's plan.

As Savathûn's ritual was underway, pulling the Traveler into her throne world, the Guardian exposed more long-lost memories of young Sathona, revealing that the Witness was responsible for tricking the proto-Hive into unleashing the Worm Gods and blame the Traveler for an imminent cataclysm on their homeworld of Fundament. As a result of the Guardian's actions in disrupting the ritual, the Traveler was returned to Earth.

Gameplay
The Traveler grants the Guardians the mysterious powers that they wield, through a symbiotic relationship with the Ghosts; personal artificial intelligences housed in small shells, which serve as the companions of Guardians. Ghosts form this connection with a single guardian when they resurrect them for the first time, and after that point a Ghost cannot give it's Light to any other guardian. Ghosts are intelligent, with human-like personalities and unique, personal sets of beliefs, opinions and theories. Strangely, Ghosts seem to posses very little innate knowledge about the Traveler and have been known to debate the finer details of the Light among themselves.

The Ghosts were assumed to be made by the Traveler itself in its dying moments during the First Collapse, although this theory is not actually confirmed by hard evidence. Within the Tower, The Speaker acts as the representative of the Traveler and a sort of spiritual leader for the Guardians, and has always been a Guardian themselves. The most recent Speaker was captured and eventually executed by the Consul aboard Ghaul's flagship during the Red War.

Trivia

 * According to Fenchurch Everis, the inside of the Traveler "smells faintly of vanilla." Whether this is true or not is unknown.
 * According to Xur, there is a dark mirror of the Traveler.
 * Calus claims to have known of the Traveler before its arrival to the Solar System.