Streaming services are currently obsessed with turning beloved young adult novels into TV series. HBO Max is gearing up for its Harry Potter show, while Percy Jackson and the Olympians returns for a third season on Disney+. But long before these adaptations hit the small screen, one series paved the way: Shadowhunters, based on Cassandra Clare's The Mortal Instruments books.
The franchise first attempted a film adaptation with The Mortal Instruments: City of Bones in 2013, but it bombed critically and commercially. However, the story found new life as a Freeform TV series that ran for three seasons. Here's why Shadowhunters deserves a second look and how it set the template for modern YA adaptations.
What Is 'The Mortal Instruments' About?
The story follows teenager Clary Fray, who discovers she's part of a secret world of Shadowhunters—half-angel warriors tasked with protecting humanity from demons, vampires, werewolves, and other supernatural threats. Clary joins their ranks and soon clashes with the villainous Valentine Morgenstern, who wants to summon the Angel of Death. Along the way, she falls for the enigmatic Jace Herondale, only to learn they might be related (yes, that really happens).
The books have been compared to Twilight and Harry Potter, and for good reason: Clare originally wrote The Mortal Instruments as a Harry Potter fanfiction before changing the characters and setting. The result is a series that feels like a mashup of both franchises—a teenager discovering a hidden magical world, a love triangle, and a prophecy about saving the world.
Why the Movie Failed
City of Bones was a disaster. Critics panned it for being derivative of Twilight and The Hunger Games, and the lead actors Lily Collins and Jamie Campbell Bower had zero chemistry. The film crammed too much mythology into one movie, wasting a talented supporting cast that included Robert Sheehan and Jared Harris. It bombed at the box office, killing plans for sequels (one of which would have featured Sigourney Weaver).
But the cast bounced back: Bower later played Vecna in Stranger Things, and Sheehan became a fan favorite in The Umbrella Academy. The movie's failure also proved that the books needed more room to breathe—something only a TV series could provide.
How 'Shadowhunters' Fixed Everything
When Shadowhunters premiered on Freeform in 2016, it corrected nearly every mistake of the film. Katherine McNamara took over as Clary, delivering a performance that made the character feel like a real teenager—flawed, emotional, and relatable. The series stayed closer to the books, using the longer format to develop characters and plotlines. For example, the introduction of vampires and werewolves was handled with care, and Simon's transformation into a vampire got the emotional weight it deserved.
The show also made better use of its supporting cast, including Isaiah Mustafa as the werewolf Luke Garroway. McNamara and co-star Dominic Sherwood recently launched a podcast called Return to the Shadows, where they reminisce about their time on the series.
Why 'Shadowhunters' Still Matters
Though City of Bones is largely forgotten, Shadowhunters remains a cult favorite. The cast became regulars at comic conventions, and fans even tried to organize their own convention. The series proved that YA adaptations can thrive on TV, paving the way for shows like Shadow and Bone and the upcoming Harry Potter series. If you're looking for a fantasy fix that blends the magic of Harry Potter with the romance of Twilight, Shadowhunters is the perfect binge-watch.
For more fantasy recommendations, check out our list of the best fantasy shows of 2026 or dive into high fantasy books with inventive magic systems.
