The Avengers #169

The stakes couldn't be higher in this 1978 Marvel thriller, as the cover — penciled by Dave Cockrum and inked by Joe Sinnott — lays out the crisis in bold terms: "The Avengers must find the 3 Dooms that threaten tomorrow… or it's the end of the world!" Captain America charges forward at the center of the composition, flanked by a winged lion-like creature and a hulking beast, while Iron Man streaks across a battle-torn cityscape in the background and Vision hovers watchfully in the corner above. That blazing, jagged red sphere dominating the center of the cover radiates genuine dread, making it clear Earth's Mightiest Heroes are facing something on a truly global scale.