Deus

Deus is an antagonist in Xenogears. It is fought twice, once in Mahanon, and again in its core. It is referred to as a god by many of the Xenogears world's inhabitants. But in reality, it is a biological weapon created by humans in ancient times on another planet. Although it is the penultimate boss, because the boss after Deus is extremely easy, Deus is considered by many to be the final boss of the game.

Appearance and Personality
Deus has several forms. Its first form, known as "Omega 1", was seen on the display screen of the Eldridge in the opening scene. This is the form that the party fought in Mahanon. After being defeated in its first form, and its body was move to Merkava, Deus takes the form of a large dome with seven eyes. After Merkava rises from the earth, Deus begins terraforming to fuse with the planet. When confronted by the party inside its body, Deus is surrounded by four orbs, Metatron, Sundel, Marlute, and Harlute with the center being its true body which takes on an angelic appearance.

Due to being an artificial intelligence, Deus displayed little to no personality.

Story arc
Deus is a bioweapon created by humans on another planet; an interplanetary invasion system in ancient times, it is capable of taking control of a targeted planet. However during a test run, Deus ran out of control and destroyed a planet, and its creators deemed it a threat and has shut down the project. In order analyze the cause of the incident, Deus was broken down into several components on the Eldridge, a passenger ship, to be transported to another planet. On the way, Deus became self aware and tried to take over the ship over a nearby planet. The captain of the ship then orders everyone to evacuate the ship, only for Deus to hack into weaponry to destroy all the escape shuttles, forcing the captain to sacrifice himself to detonate the ship in a last ditch effort to destroy Deus. The explosion sends the debris of the Eldridge and Deus crashing into the planet, but not before detaching the from its core and Kadomony activating System Hawwa, creating the first Miang for Deus's eventual resurrection.

9999 years later, after the Gazel Ministry uses the Gaetia Key to turn a majority of the planet's inhabitants into Wels for replacement part for Deus, Mahanon rises up from the ocean in order to retrieve its body and revive it. After convincing Elly to stay behind, Fei and the party ventures into Mahanon where they were confronted by the nuclei of Deus. After defeating it, the creature disintegrates, allowing the party to venture further into Mahanon in which they discover Razael's Tree giant computer containing considerable information about Deus and the Eldridge. Just as they were about collect data on the Zohar, Grahf and the Solarian forces ambush the party with Grahf defeating the party with ease. Krelian orders Grahf to spare the party and orders his forces to be crucify the party at Golgoda to lure Elly.

After capturing Elly, Krelian recreates Merkava, using nanomachines. Inside, Deus takes the form of a large dome with four eyes. When the party enters the central chamber where Deus is found, they spot Elly crucified. Krelian reveals that he's planning to sacrifice her to fully awaken Deus before Miang takes on the party in her Omnigear, Opiomorph. After the party defeats her, Deus begins to absorb the Anima Relics of the party's Omnigears.

Just as Elly was about to be sacrificed, Ramsus suddenly appeared and apparently kills both Miang and Elly in a rage for their roles in manipulating his life. Unfortunately, both survived with Miang possessing Elly and Krelian due to majority of his body comproised of nanomachines; by possessing Elly, Miang has awakened as the last Miang. She then proceed to reveal the true purpose of Deus, the Zohar and herself to the party before departing with Krelian to reunite with Deus.

Deus then detaches itself from tubes that are connected to it and sinks beneath the green liquid with Fei giving chase, while the others escape. After that Deus begins to terraform with the planet, rising from the remains of Merkava. After Fei reunites with his fragmented personalities, he and his comrade's goal is to reach its core to save Elly and free the Wave Existence that is trapped in the Zohar.

When the party confront its true body, it is surrounded by four spheres, Metatron, Sundel, Marlute, and Harlute. Fei has the option of either destroying the spheres before facing Deus, or directly confronting it. Regardless, when faced by the party, Deus took the form of a large angelic being. After an exhausting battle, the party manages to defeat Deus, freeing the Wave Existence. As the Wave Existence is about to depart the Zohar and exert a massive amount of energy, Elly moves Deus towards space in order to ensure that the planet isn't destroyed. Fei follows her in Xenogears and the two are reunited after he defeats the final version of Miang, Urobolus. The two encounter Krelian one last time then return to the planet in Xenogears, erasing Deus for good.

Lore

 * Deus gains its power from the Zohar Modifier.

As a boss

 * Deus (Mahanon)
 * Deus (Deus)

Trivia

 * Alpha, the main antagonist of Future Redeemed took on a form similar to Deus in the final battle.