General Gálvez, also identified as Zeo Gattler in some sources, serves as the primary antagonist. A high-ranking military leader from the polluted planet S-1, where survivors live underground, he rejected scientific environmental restoration. Gálvez seized power by assassinating S-1's emperor and framing a team of environmental scientists for the act, enabling his control and mobilization for an off-world invasion.

He commanded surviving S-1 civilians onto the fortress ship Algol to conquer a new world. Targeting Earth with his Aldebaren Army, Gálvez ordered the destruction of a nearby Martian colony, demonstrating his readiness to eliminate populations for territory. His leadership is defined by ruthless pragmatism, prioritizing conquest over environmental or ethical solutions.

A personal conflict fuels his actions: Marin Reigan, son of the lead scientist Gálvez framed and killed. This intensifies when Marin kills Gálvez's subordinate, who is also the brother of key commander Aphrodia, weaving a vendetta into the military conflict and influencing Aphrodia's actions.

During Earth's invasion, Gálvez employed extreme tactics to crush resistance. His most devastating act deployed artificial suns to melt Earth's polar ice caps, triggering catastrophic tsunamis that flooded coastlines and caused massive casualties, underscoring his commitment to total victory through indiscriminate destruction.

A pivotal revelation exposed that S-1 and Earth are temporally linked versions of the same planet. Gálvez's earlier actions—fleeing S-1's pollution and traveling back in time—inadvertently caused the very environmental collapse he sought to escape, creating a closed time loop where his invasion forged the polluted future he originated from.

His fate concluded with the detonation of a radioactive core within the Aldebaren fleet, engineered by his adversaries, eliminating him and much of his command structure during the conflict's climax.