Alien God

"A change in the situation has been confirmed. A proposal for you chosen ones, a suggestion for you abandoned ones. If you desire glory, then choose the ressurection. If you desire idleness, then choose the eternal sleep. God is fine with either one."

- The Alien God to the Crypters

"I am the being from a different star that will descend upon this star. The tree of fantasy will initialize this planet. It'll build up a new myth. Crush down the Greater History of Man, and construct God with your own hands. Build up the allows to receive me."

- The Alien God to Kadoc Zemlupus

The Alien God is the overarching antagonist of Fate/Grand Order: Cosmos in the Lostbelt. It is a mysterious alien lifeform who arrived upon Earth in late 2016, seizing the chance left by Goetia's defeat.

Overview
The nature of the Alien God tends to be a mystery, since not even his three Alter-Ego Emissaries or Kirschtaria Wodime ever grasped its true nature.

The Alien God sought to wipe out the Pan-Human History and replaced it with the Age of Gods. After freezing Chaldea through its followers, it summoned the seven Lostbelts upon Earth and planted the Fantasy Trees within them, working with the seven Crypters (formerly Chaldea A-Team masters whom he revived) and taking control over the Lostbelts.

In the Atlantis chapter, the journal of David Bluebook revealed his discovery that the Alien God was summoned through human cause, after the government of the United States secretly experimented one of its kind within Area 51 through their newfound technology. It unintentionally brought the Alien God upon Earth and attack humanity in order to avenge his kin.

Kirschtaria willingly worked with the Alien God, but he revealed that he had no intention to work for it, revealing he had his own agenda to make Greek Lostbelt a new reality and deviate from the Alien God's entire plan.