OVA
Description
Emperor Zuul reigns as the supreme ruler of the Gishin Empire, originating from the resource-depleted planet Gishin in the MG-69 Galaxy. His obsidian visage features piercing green eyes and a vent-shaped mouth, crowned by a helmet bearing a red glowing orb on the forehead. A purplish-black robe shrouds most of his form, accented by onyx chest armor encircled with five red orbs around his neck.

Consumed by the need to restore Gishin's resources, Zuul embarks on galactic conquest. After suffering defeat in the "One Month War" against Earth, the United Nations, and Eldar forces, he targets Earth for vengeance. His retribution involves sending the infant Mars to Earth alongside the robot Gaia, which harbors a solar-system-destroying bomb programmed to detonate upon Mars's death. Raised as Takeru Myojin, Mars develops loyalty to humanity and ultimately defies Zuul's command.

Zuul embodies extreme narcissism, prioritizing his empire's glory while feigning concern for subordinates. He displays profound intolerance toward failure and deep paranoia toward perceived threats, especially Earth's defenders and the rival planet Eldar. His formidable abilities include teleportation, growth to colossal proportions, and emitting an "Anti-God Pulse" capable of disrupting energy-based systems.

A key element of his past involves manipulating Marg, Mars's twin brother. Following the death of Marg's parents and the destruction of his guerrilla group, Zuul captured and brainwashed Marg into serving the Gishin Empire. Zuul later coerces Marg into opposing Mars, extending his influence to torture Marg's soul even after death.

Zuul's true nature transcends physical form; he is a cosmic entity whose consciousness permeates the universe through dispersed cells, enabling resurrection after physical destruction. He claims dominion over the afterlife, inflicting suffering upon the deceased.

In the final conflict, Zuul battles God Mars using a Combined Energy Attack, fusing the power of five robots (Sphinx, Uranus, Titan, Shin, Ra) with Gaia. Though defeated, he asserts his immortality via universal cellular presence, threatening inevitable rebirth.

The OVA "Untold Legend" depicts Zuul as the architect of Marg's tragedy, orchestrating his suffering and brainwashing, reinforcing Zuul's relentless pursuit of control through psychological and physical domination.