Complete Monster: General Zee (Leader Zytel in the original), supreme leader of the Gothamite race and the genius who designed the Terror Star to preserve the race, opens the series by ordering a genocide that exterminates ninety percent of humanity to claim earth for Gothamites. However, it is later revealed that the Terror Star had a flaw Zytel was well aware of. Instead of doing anything to save his people,he let hundreds of millions of Gothamites die when life support failed, intending to flee to a changed earth with preserved Gothamite cells to restart the race with himself as their leader. Upon discovery, Zytel promptly tries to murder the subordinate confronting him, obsessed only with his legacy and control over the people of Gotham.
Fridge Horror: What killed off 90 percent of humanity wasn't alien bombardment, but the effects of the earth's axis of rotation tilting further. Now in the end, Terra-Star comes close enough to Earth in its way to plunging into the sun, that the Earth's axis tilts back to where it was. If the first tilt killed off 90% of the population, imagine the further damage caused by the second tilt!!