In 1969, Sheldon Feldner contacted Marvel Comics, asking if one of Marvel's artists would be interested in designing costumes for a production of William Shakespeare's play Julius Caesar by the University Theatre Company at Santa Cruz at the newly-built Cowell College of the University of California at Santa Cruz.
As luck would have it, the Kirby family had recently moved to California, and Stan Lee recommended that Feldner contact Jack Kirby.
Jack Kirby {wiki} was the creator of such characters as Captain America, The Fantastic Four, and the X-Men. But he went to work designing not only the costumes but also a poster for the student production. His sketches, and some pictures of the actual costumes, are posted at the Kirby Museum. Link -via Metafilter