Thanos was a warlord and genocidal maniac from Titan, whose primary goal was to bring stability to the universe. He believed that its enormous population would inevitably deplete all available resources, condemning the species to extinction. To achieve this, Thanos dedicated himself to finding the Infinity Stones, as their power would allow him to directly and randomly kill half of all life in the universe. This led him to forge alliances with the villains Loki and Ronan in their respective campaigns against Earth and Xandar, but he ended up losing a significant portion of his resources and the loyalty of his daughters, Gamora and Nebula. Ultimately, Thanos lost patience with his subordinates and decided to search for the Stones himself, thus beginning the Infinity War. On his journey, he and his Black Order invaded Nidavellir, Xandar, Earth, and Knowhere, even murdering Loki, along with half of the surviving Asgardians, and his daughter Gamora, to obtain the Soul Stone on Vormir. This prompted the Avengers, the Masters of the Mystic Arts, the Guardians of the Galaxy, and the nation of Wakanda to confront him, but despite their combined efforts and Thor's wrath, Thanos ultimately triumphed over his enemies after completing the Infinity Gauntlet and performing the Snap. He then relocated to Titan II to live in peace and destroyed the Infinity Stones. Finally, Thanos was ambushed by the surviving Avengers, only to be decapitated by Thor.

Lord Darkseid, formerly known as Uxas, is an extremely powerful, millennia-old New God warlord who inhabits and rules the planet Apokolips. In his quest for the Anti-Life Equation, Darkseid led a vast army of Parademons, along with his heralds DeSaad, Steppenwolf, and Granny Goodness, against the Earth's Unity, suffering his first defeat at the hands of its defenders. After centuries of searching, Darkseid was informed by Steppenwolf, who sought redemption after betraying him, that the Anti-Life Equation was located somewhere on Earth. Steppenwolf promised to grant him the Mother Boxes, piquing Darkseid's interest. However, he watched the Justice League's defeat with frustration and decided to invade the planet to claim the Anti-Life Equation for himself.