Infinity is the cosmic entity that defines the entirety of space and its occupants. Together with Eternity it encompasses all of creation, representing both time and space. Infinity was "born", along with the other abstracts, with the "Big Bang". Each universe has its own Infinity, all overseen by the Living Tribunal and its enigmatic master, the "One Above All" (not the Celestial by the same name).
Long ago the Asgardian all-father Odin added a tiny sliver of infinity's powers to his own powers, which were later stolen and corrupted by the Asgardian death-goddess Hela. Christened Infinity, the sliver threatened to destroy the universe until stopped by Thor. More recently, the newly disembodied Inhuman/Deviant hybrid Maelstrom, whose atoms had been spread across the universe, learned of the existence of the abstract entities. He slew and replaced the cosmic being Anomaly. Aided by Oblivion, he sought to collapse the universe into a single anomalous point, bringing all that is to Oblivion's realm, and secretly planned to become the new Oblivion in the process. As part of his plan, Maelstrom killed Eon's protector Quasar,stealing his quantum bands and Eon's powers. Maelstrom then created a black hole in the center of the universe strong enough to pull all of existence. Quasar's energy-ghost contacted Infinity, who revealed its role in recent events to make him its avatar. Quasar killed Maelstrom and had almost reversed the spatial explosion when Oblivion pitted him against its avatar, the reborn Maelstrom. The two were evenly matched until Quasar realized that an earlier retroactive act by the cosmic entity Origin had made him the superior anomaly and used that knowledge to destroy Maelstrom. Infinity and Oblivion summoned their counterparts Eternity and Death to negotiate a new pact between their forces allowing, amongst other things, Quasar's resurrection.
Infinity later joined with other abstracts in confronting former Damage Control employee Edifice Rex. A merged Infinity/Eternity bound Adam Warlock's evil side, the Magus, inside Warlock's soul gem. Infinity witnessed Roma's attempt to keep Franklin Richards' powers from overwhelming the universe, and subsequently gave the Shape-of-the-Worlds faux-medieval creation "Eurth" a permanent existence. Later, the merged Infinity and Eternity were almost driven mad by the coming death of reality-anchor Atlez, but were restored when Warlock brought in his replacement Atleza. When Thanos used the Heart of Infinite to destroy all reality, including Infinity, Warlock convinced him to recreate the universe and restore all abstracts.