Quick Answer: Before ABC created Once Upon a Time, the network originally planned on creating a series based on Fables, a comic book series published by Vertigo, an imprint of DC Comics. However, after Fables failed to get picked up, ABC used the same premise of fairy tale characters in the real world to create Once Upon a Time using Disney characters. Although Once Upon a Time is separate from Fables and the Fables-inspired Telltale game The Wolf Among Us, it shares many striking similarities in terms of characters, setting, and themes.
For over a decade, television networks attempted to adapt Bill Willingham’s acclaimed comic book series, Fables. Even if you don’t know the comics, the premise of Fables might sound familiar: fairy tale characters are forced into the real world where they live in a community hidden from the rest of society. Although Fables failed to become a television series, that didn’t stop television networks from making their own versions of this premise.
In 2005, NBC bought the rights to Fables but failed to get it past the scripting stage. Eventually, NBC produced Grimm (2011 - ), a police procedural set in a world where fairy tales and the supernatural are real. Then, in 2008, ABC picked up the rights to Fables and began developing their own adaptation. But this, too, failed. Although ABC didn’t end up adapting Fables, two executive producers/writers of Lost (2004 - 2010), Adam Horowitz and Edward Kitsis, had an idea for a series that would explore the fairy tale world alongside the real world. This idea later became Once Upon a Time (2011 - ). The show creators of Once Upon a Time said that they have read several issues of Fables, and while the two concepts are similar, the comic and Once Upon a Time are telling two different stories.
Snow White and Bigby Wolf from Fables
Perhaps the closest that Fables got to becoming a television series is the Telltale video game The Wolf Among Us (2013 - 2014), which is based on the comic book series. Through its episodic structure, The Wolf Among Us is essentially an interactive television show. However, unlike Once Upon a Time, The Wolf Among Us does not use the “disneyfied” versions of fairy tales. Instead, The Wolf Among Us takes on a much more cynical tone as it places these fairy tale characters in a sinister and violent world.
Both Once Upon a Time and The Wolf Among Us are not exactly subtle in naming their settings, which are Storybrooke and Fabletown, respectively. Both these communities are hidden from the real world (or at least they try to be) and the inhabitants are all fairy tale characters who were banished or forced to leave their fictional homelands.
Many of the same characters are seen in both, from Snow White to Beauty and the Beast. First, we have the protagonists: Emma Swan (Jennifer Morrison) in Once Upon a Time and the Big Bad Wolf/Bigby Wolf (Adam Harrington) in The Wolf Among Us. Both characters work in law enforcement as their respective town’s sheriff. They must deal with the crimes that plague the fairy tale citizens, whether it be a murder or a curse.
Emma Swan (Jennifer Morrison) in Once Upon a Time
Bigby Wolf (Adam Harrington) in The Wolf Among Us
Then we have Snow White. In Once Upon a Time, Snow/Mary Margaret (Ginnifer Goodwin) is a schoolteacher and Emma’s mother. In The Wolf Among Us, Snow (Erin Yvette) is deputy mayor and Bigby’s partner. In both versions, Snow works with the protagonists to help them solve mysteries and problems in their respective communities
Snow White/Mary Margaret (Ginnifer Goodwin) in Once Upon a Time
Snow White (Erin Yvette) in The Wolf Among Us
For the antagonists, we have Storybrooke's Evil Queen/Regina (Lana Parilla) and Fabletown's Ichabod Crane (Roger Jackson). Both villains act as mayor for their respective communities, although the fairy tale inhabitants don’t necessarily like them. Other than their shared profession, the pair is not that similar since Regina has the potential to be good while Ichabod Crane is, by comparison, purely selfish and evil.
Regina (Lana Parilla) in Once Upon a Time
Ichabod Crane (Roger Jackson) in The Wolf Among Us
As for supporting characters, we see some of the same fairy tale citizens in both towns. For example, we have Beauty (Melissa Hutchison) and Beast (Gavin Hammon) in The Wolf Among Us and Belle (Emilie de Ravin) and Rumpelstiltskin/Mr. Gold (Robert Carlyle) in Once Upon a Time. Also, the Magic Mirror plays a role in both series as he is used by Regina and Ichabod Crane for malicious purposes.
Belle (Emilie de Ravin) and Rumpelstiltskin (Robert Carlyle) in Once Upon a Time
Beast (Gavin Hammon) and Beauty (Melissa Hutchison) in The Wolf Among Us
Of course, as seen with the Magic Mirror, magic exists in the worlds of Once Upon a Time and The Wolf Among Us. Many of the magical and fairy tale items in both universes are found in pawn shops. In Once Upon a Time, Mr. Gold owns and operates Mr. Gold Pawnbroker & Antiquities Dealer. In The Wolf Among Us, the Jersey Devil manages the Lucky Pawn. Both these pawnshops sell magical items that used to belong to fairy tale inhabitants before the characters were forced into the real world. Some of the same magical spells are seen, too. For example, glamours (or shapeshifting) are heavily used in both series to disguise the appearances of the characters.
Fans of Once Upon a Time who want a grittier interpretation of fairy tales might be interested in reading Fables or playing The Wolf Among Us. Fans of The Wolf Among Us might like Once Upon a Time’s charming and quaint setting with its reinterpreted Disney characters. However, while Once Upon a Time is aimed for a broad audience, The Wolf Among Us is rated Mature 17+. Although the two share many things in common, one should be wary of some of the differences before jumping into The Wolf Among Us or Once Upon a Time.