How did Watchmen change what superhero stories could be?

The answer

Alan Moore and Dave Gibbons' Watchmen, published by DC Comics from September 1986 to October 1987, deconstructed the superhero genre by presenting morally ambiguous characters grappling with real-world politics, nuclear anxiety, and psychological trauma. Alongside Frank Miller's The Dark Knight Returns and Art Spiegelman's Maus (both 1986), Watchmen proved comics could deliver sophisticated adult storytelling. DC executive Paul Levitz observed that Watchmen 'set off a chain reaction of rethinking the nature of superheroes and heroism itself, and pushed the genre darker for more than a decade.' It became the only graphic novel on TIME magazine's list of 100 greatest English-language novels. Its influence spawned an entire era of psychologically complex, morally relative superheroes across comics, film, and television.