Charles Atlas has been in the business of selling bodybuilding courses for more than 70 years. Advertisements for Atlas's bodybuilding courses, which have appeared in DC Comic books, have included a one-page comic strip story titled "The Insult that Made a Man out of Mac." In the storyline: (1) a bully kicks sand in Mac's face at the beach; (2) after taking the Atlas course, the skinny Mac develops a muscular physique; (3) Mac finds the bully, again on the beach, and punches him, for which he receives newfound respect, particularly from his female com- panion; (4) in the final panel, the phrase "HERO OF THE BEACH" appears as a halo-like formation hover- ing over Mac's head. Mr. Atlas registered Mac with the Principal Register as the before and after characters of "Skinny" and "Joe." "Joe" is Mac in his muscular form with the leopard-skin trunks.
DC Comics created a character known as Flex Mentallo, who like Mac, came to be imbued with extraordinary strength. Flex Mentallo, once a scrawny weakling who has sand kicked in his face by a bully, returns to the beach with his muscular physique, and like Mac in the Atlas comic ad, he beats up the bully and becomes "the Hero of the beach."