It's a well-known part of Harley Quinn's history that she first appeared in an episode of 1992's Batman: The Animated Series as a one-off character, whose popularity led to a recurring role and eventually her current status as one of DC's biggest stars.
But she's far from the only well known comic book character who first appeared in movies, TV, and even radio before coming to comics. In fact, we've got a list of 20 famous examples - some of whom may surprise you.
And yes, rest assured, Harley is on the list!
20. Isis (DC)
The now-unfortunately named Isis originally debuted in the '70s on the Shazam TV show, before getting her own short-lived spin-off series. She came to comics in the 2006-2007 weekly title 52 as the bride of Black Adam who shares his powers. Isis' comic story ended tragically, and she hasn't been seen since.
19. Darcy Lewis (Marvel Comics)
Darcy Lewis first appeared in the MCU as the assistant to Natalie Portman's Dr. Jane Foster in 2011's Thor, played by Kat Dennings. She made the move to Marvel Comics in 2023's Scarlet Witch #1 as the manager of Wanda Maximoff's occult shop.
18. Red X (DC)
Red X started out as a secret alter ego for Tim Drake in the Teen Titans animated series in one of its most beloved arcs, featuring the team's arch enemy Slade Wilson. The Red X concept recently came to comics, with the character's secret identity once again forming the center of a Teen Titans mystery - though the solution, involving time travel and other comic book weirdness, is hard to explain.
17. Reptil (Marvel Comics)
Reptil is a teen hero with the actually kinda super cool power to embody different aspects of dinosaurs. If that sounds extra kid friendly, you're exactly right, as Reptil originally debuted in kid-focused Marvel Super Heroes Super Show before being recruited into the Avengers Academy training program in Marvel Comics.
16. Erik Selvig (Marvel Comics)
Dr. Erik Selvig was originally introduced as Jane Foster's mentor in 2011's Thor, with actor Stellan Skarsgaard going on to reprise the role multiple times in the MCU, including in 2012's Avengers. He was introduced in comics in 2016's Avengers: Standoff event as the guardian of a sentient Cosmic Cube with the power to alter reality.
15. King Tut (DC)
For those who are familiar with the 1966 Batman TV series starring Adam West and Burt Ward as Batman and Robin, the villainous King Tut is no stranger. But the odd Egyptian-themed villain, played by Victor Buono, wasn't adapted into mainstream DC comic book continuity until 2009's Batman Confidential #26, in a story where Batman teams up with the Riddler. King Tut later returned in 2019's Riddler: Year of the Villain #1 one-shot as a rival of Riddler and enemy of Batman.
14. Morph (Marvel Comics)
"This one's for you, Morph!" You probably read that in the voice of Cal Dodd as Wolverine on the 1992 X-Men: The Animated Series, as he bellowed it after the shocking death of the shapeshifting mutant Morph. An original creation for the show, Morph was later adapted to Marvel Comics in an admittedly different form in the 1995 event Age of Apocalypse as a mutant hero from an alternate reality.
13. Ursa and Non (DC)
Unlike Superman 2's main villain General Zod, his fellow Phantom Zone criminals Ursa, the femme fatale, and Non, the mute muscle, were originally created for the 1980 movie - though Zod did have other sidekicks in comics before and after Superman 2. Ursa and Non were introduced in comics in 2006, when Superman director Richard Donner, who had helped create them for the film, had a brief run as the co-writer of Action Comics.
12. Wendy, Marvin, and Wonder Dog (DC)
Much like the Wonder Twins who replaced them (more on them in a moment), Wendy, Marvin, and Wonder Dog served as the comic relief sidekick for a certain era of the Super Friends TV show in the '70s. They didn't come to comics until 2006, where Wendy and Marvin were introduced as the young genius support staff of the Teen Titans. Weirdly (and horrifically), the duo didn't originally have Wonder Dog with them in comics. He was introduced some time later as a stray dog the pair found which turned out to be a hellhound that killed Marvin and maimed Wendy.
11. The Wonder Twins (DC)
Despite being something of cult icons thanks to their role in the '70s Super Friends cartoon, the Wonder Twins Zan and Jayna and their pet space monkey Gleek took almost 20 years to come to comics. Oddly enough, the comedic superhero duo, who have the powers of transforming into water (Zan) and different animals (Jayna), made their comic book debut in the '90s in a title called Justice League Extreme - not quite what you'd expect for such a goofy pair. A 2019 Wonder Twins limited series updated them a bit for the modern era, while also harkening back to their cartoonish roots.
10. HERBIE (Marvel Comics)
HERBIE the robot is one of the more notorious examples of a character who first debuted in an animated series. In the '70s, Hanna Barbera created a new Fantastic Four cartoon - but with only three of the original FF. Johnny Storm, the Human Torch, was taken out of the line up out of fear that children would light themselves on fire to emulate him, and replaced by HERBIE the bumbling robot. HERBIE has since come to comics as a non-comedic robot sidekick, rather than a full member of the team.
9. Livewire (DC)
Livewire was originally introduced as a villain on 1996's Superman: The Animated series as a shock-jock radio host who gains electrical powers through a freak accident. After showing up as a recurring villain on Superman and the later Justice League animated series, she made it to comics in 2006 as a Superman villain, naturally, before clashing with Batgirl several times.
8. Renee Montoya (DC)
Renee Montoya debuted in 1992's Batman: The Animated Series as one of the best detectives on the Gotham City police force. That reputation followed her into comics, where she eventually took on the identity of the Question as the handpicked successor to the original, Vic Sage. She's been the Question off and on since - and she's also had an on-again-off-again romantic relationship with Batwoman.
7. Jimmy Olsen and Perry White (DC)
As much as they may be iconic comic book characters - with Jimmy Olsen even starring in multiple comic titles of his own over the years - Daily Planet employees and Superman supporting characters Perry White and Jimmy Olsen originally debuted on the influential Superman radio show of the '40s and '50s before quickly being adapted into comics. The long running show also introduced numerous other aspects of superhero mythology, including Kryptonite.
6. Kaldur'ahm (DC)
Kaldur'ahm first debuted on the animated series Young Justice as a brand new Aqualad from Atlantis. He was quickly adapted to comics as a resident of Mera's underwater home nation of Xebel, who was fathered by the original Aquaman's nemesis Black Manta. In the 2022 title Aquaman: The Becoming, Kaldur became the second hero in DC history to take on the name Aquaman, using it concurrently alongside Arthur Curry, the original.
5. Laura Kinney (Marvel)
Laura Kinney, the second Wolverine, made her original debut in the early '00s animated series X-Men: Evolution before quickly crossing over into Marvel Comics in the short lived title NYX. She's currently starring in an X-23 limited series which revives her clone designation as a genetic copy of the original Wolverine.
4. Phil Coulson (Marvel Comics)
Actor Clark Gregg debuted as SHIELD agent Phil Coulson in a minor role in 2008's Iron Man, going on to become the pal and confidant of the original MCU Avengers, and the star of the Agents of SHIELD TV show. In comics, he had a much stranger path. Though he started as a SHIELD agent, he eventually became a villain who made a deal with Mephisto to temporarily remake reality with himself as the president of the United States.
3. Terry McGinnis (DC)
Terry McGinnis was originally the star of the animated series Batman Beyond, where he was the young protege of an aging Bruce Wayne in a future version of Gotham City. That story was later adapted to comics not just in a comic adaptation of the show itself, but in the mainstream DC Universe where Terry has been shown as the Batman of a possible future, with original comic adventures and continuity not tied to the animated series.
2. Firestar (Marvel Comics)
Firestar first appeared in the 1981 animated series Spider-Man and his Amazing Friends as one of the eponymous pals alongside Iceman. She later debuted in Marvel Comics as a member of the villainous Hellions, before quickly reforming as a member of the New Warriors and later the Avengers. She most recently came full circle as a current member of the X-Men.
1. Harley Quinn (DC)
Harley Quinn is undoubtedly one of the most famous and successful examples of a character making the leap from TV to comics. She debuted in an episode of 1992's Batman: The Animated Series as a one-off henchwoman for the Joker, but her popularity led her to become one of the show's main recurring characters. Harley then made the jump to comics, where she's become a leading woman all her own, even crossing back into her own starring animated series - and of course her popular portrayal in several films by Margo Robbie.