Watchmen is set in an alternate reality that closely mirrors the contemporary world of the 1980s. The main difference is the existence of superheroes. Their presence in this history has altered the outcomes of real-world events such as the Vietnam War and presidency of Richard Nixon. Although the cast of Watchmen are commonly called "superheroes," the only character in the principal cast who possesses superhuman powers is Doctor Manhattan (although Ozymandias is said to possess "peak human" abilities and in one case exceeds them by catching a bullet). In the comic, they refer to themselves as "costumed adventurers" or less frequently, considering its comparatively negative connotations, "masked vigilantes."
As stated above, the cast of Watchmen was initially based upon old MLJ Comics and then Charlton Comics characters. The Comedian (Edward Blake) is based on Peacemaker. Doctor Manhattan (Jon Osterman) is derived from Captain Atom, while the first and second Nite Owls (Hollis Mason and Dan Dreiberg) are based upon Blue Beetle. Thunderbolt serves as the inspiration for Ozymandias (Adrian Veidt), while the Question and Mr. A do the same for Rorschach (Walter Kovacs). Finally, the first and second Silk Spectres (Sally Jupiter and Laurie Juspeczyk) are roughly analogous to Nightshade, but only in that they are female. Moore has stated that the Silk Spectres are more directly inspired by elements of Black Canary and Phantom Lady.