The X-Men #6

In "Sub-Mariner! Joins the Evil Mutants," Stan Lee and Jack Kirby deliver a pivotal moment in early X-Men history, as Professor Xavier and Magneto both speculate on Namor’s possible mutant status—leading to a dramatic invasion of Atlantis. With Chic Stone’s dynamic inks and Stan Goldberg’s vivid colors, the issue captures the clash of ideologies and the Sub-Mariner’s fateful choice, all rendered in Kirby’s bold, iconic style.