Off the scale
One of these two was never ranked, so this cannot move a ranking it is not in.
Again nothing moves — the victim is not a participant in the setting but the setting itself — and yet this is the only pairing on the site where an abstraction dies `shown` rather than `stated`. That alone earns the page. Read it directly against the Living Tribunal pairing, where the same killers do a comparable thing on weaker evidence and the site has to say so. First place is argued from completing something at a scale nobody else on the ladder attempted; this is the portion of it that was actually put on the page.
The Beyonders killed Eternity in New Avengers (2015).shown
Eternity, Infinity, Lord Chaos, Master Order, the In-Betweener
Named as the killers of the Living Tribunal and the cause of the incursions destroying the multiverse. — 2015
The multiverse ends, leaving one patchwork world assembled from the survivors.
They killed the Living Tribunal, they killed Celestials, and then they collapsed the entire multiverse to a schedule, universe against universe, until one was left. Nobody else here completed a plan that size. The contested tag is for the obvious objection: they barely qualify as characters, they have no dialogue, and their motive is never explained. The wreckage is still on the page.
Introduced as the personification of the universe itself. — 1965
Is defeated by Thanos wielding the completed Gauntlet, who then takes his place.
Not a being in the universe. The universe, given a shape so that characters have something to argue with. Thanos has beaten him and taken his place, and when the Chaos King came for everything, Eternity declined to fight on the grounds that they would both stop existing — which says less about him than about what this list is actually measuring.
One death in one work. It is the only place the record puts these two in the same room, and it is evidence about that meeting and nothing wider — not a general matchup, not a rematch, and not a ranking of its own. The ladder above it is argued from everything either of them has been shown doing; this page is argued from one citation. Where the two disagree, the disagreement is the point, and it stays visible rather than being resolved by whichever of them happens to be on this page.
Both entries carry their full receipts on the Marvel ranking — 4 citations between them.