Simek's work included such landmarks as The Fantastic Four #1 (Nov. 1961) and Spider-Man's debut in Amazing Fantasy #15 (Aug.

[4] Simek's first confirmed credits are the 12-page lead story "The Three Super-Sleepers", a Batman-Superman team-up in DC Comics' World's Finest Comics #91 (Dec. 1957),[5] and, for the same company, the eight-page backup story "Batman's Roman Holiday", in Batman #112 (Dec.

Beginning with his first confirmed Marvel Comics credits, three Kid Colt stories totaling 18 pages in the Western Kid Colt, Outlaw #83 (March 1959), Simek became, with Sam Rosen, one of Marvel's two primary letterers, hand-drawing the word balloons and sound effects for virtually every comic produced by the company, with Simek lettering most early issues of the flagship series Fantastic Four.

Simek's final work was lettering pages 2–8 and 10 of the 32-page superhero story "Eelar Moves in Mysterious Ways" in Giant-Size Defenders #5 (July 1975), which an editorial note on the letters page describes as the last Simek completed before his death while working on the issue.

[7] Future Comic Book Hall of Famer Gene Colan, a Marvel mainstay from 1946 on, described Simek as "a real Norman Rockwell character.