The New Mutants #21

Published by Marvel Comics in November 1984, The New Mutants #21 represents a pivotal moment in the series as it marked the first professional comics work of artist Bill Sienkiewicz on the title. Sienkiewicz took over from Bob McLeod, bringing a radical shift in aesthetic that moved away from traditional superhero house styles toward an expressionistic, painterly, and surreal approach. This stylistic departure polarized contemporary readers but has since been critically canonized as a landmark moment in 1980s comic book art.

Written by Chris Claremont, the story follows the young mutants as they contend with the fallout from the Legion's emergence, a narrative arc central to the X-Men mythology. The issue is widely regarded by historians and collectors as the beginning of the 'Sienkiewicz era,' a period that elevated the series' visual language to match its complex, often psychological character development. It remains a definitive example of how an illustrator can transform the tone of an established long-running franchise.