The X-Men #21

Published in June 1966, The X-Men #21 represents a pivotal moment during the series' initial Silver Age run. Written by Roy Thomas with iconic pencils by Werner Roth, the issue continues the creative evolution of the title following Jack Kirby’s departure. It serves as a classic example of the mid-sixties Marvel house style, characterized by its focus on team dynamics and the escalating threat of established adversaries like the Sentinels, a recurring plot element during this period.

The issue is noted for its contribution to the X-Men's developing lore, particularly regarding the characters' integration into the broader Marvel Universe. Werner Roth, who often worked under the pseudonym Jay Gavin, brought a refined, illustrative approach to the team’s visual identity that differed from Kirby’s kinetic bombast, favoring a more grounded, episodic narrative structure. While early issues of X-Men were often overshadowed by the popularity of the Fantastic Four or Spider-Man at the time, this issue is now valued by historians as a crucial link in the series' long-term continuity.