A critical and commercial success, Watchmen is highly regarded in the comics industry and is frequently considered by several critics and reviewers as comics' greatest series and graphic novel. In time, the series has also become one of the best-selling graphic novels ever published. Watchmen was the only graphic novel to appear on Time 's 2005 "All-Time 100 Greatest Novels" list, where Time critic Lev Grossman described the story as "a heart-pounding, heartbreaking read and a watershed in the evolution of a young medium." It later appeared on Time 's 2009 "Top 10 Graphic Novels" list, where Grossman further praised Watchmen, proclaiming "It’s way beyond cliché at this point to call Watchmen the greatest superhero comic ever written-slash-drawn. But it’s true." In 2008, Entertainment Weekly placed Watchmen at number 13 on its list of the best 50 novels printed in the last 25 years, describing it as "The greatest superhero story ever told and proof that comics are capable of smart, emotionally resonant narratives worthy of the label 'literature'." The Comics Journal, however, ranked Watchmen at number 91 on its list of the Top 100 English-language comics of the 20th century.
In Art of the Comic Book: An Aesthetic History, Robert Harvey wrote that with Watchmen, Moore and Gibbons "had demonstrated as never before the capacity of the [comic book] medium to tell a sophisticated story that could be engineered only in comics". In his review of the Absolute Edition of the collection, Dave Itzkoff of The New York Times wrote that the dark legacy of Watchmen, "one that Moore almost certainly never intended, whose DNA is encoded in the increasingly black inks and bleak storylines that have become the essential elements of the contemporary superhero comic book," is "a domain he has largely ceded to writers and artists who share his fascination with brutality but not his interest in its consequences, his eagerness to tear down old boundaries but not his drive to find new ones." In 2009, Lydia Millet of The Wall Street Journal contested that Watchmen was worthy of such acclaim, and wrote that while the series' "vividly drawn panels, moody colors and lush imagery make its popularity well-deserved, if disproportionate", that "it's simply bizarre to assert that, as an illustrated literary narrative, it rivals in artistic merit, say, masterpieces like Chris Ware's 'Acme Novelty Library' or almost any part of the witty and brilliant work of Edward Gorey".
Watchmen was one of the two comic books, alongside Batman: The Dark Knight Returns, that inspired designer Vincent Connare when he created the Comic Sans font.
In 2009, Brain Scan Studios released the parody Watchmensch, a comic in which writer Rich Johnston chronicled "the debate surrounding Watchmen, the original contracts, the current legal suits over the Fox contract".