Marvel Comics

The second Busiek/Pérez Avengers omnibus contains the arc most frequently cited as the definitive Avengers story: Ultron Unlimited, the four-issue siege of an Eastern European nation where Ultron kills every living being and constructs an army from their remains. Busiek spent the preceding issues building Ultron's return to maximum dread, and when the assault arrives, Pérez's artwork of the Avengers standing against an enemy that has already won is among the most powerful in the character's history.

The sixth Avengers omnibus covers the conclusion of Englehart's run, centered on the Celestial Madonna storyline — one of the most ambitious Bronze Age Marvel narratives, weaving Mantis's mysterious origin through past, present, and future while simultaneously resolving the Swordsman's arc with his death in combat. Englehart used the Vision and the Scarlet Witch's relationship as the emotional spine of the era, building toward their eventual marriage in a standalone special that remains one of Marvel's most unusual romantic narratives.