Comics can, and should, be credited with creating many of the greatest fictional characters to ever grace the page. Spider-Man, Superman, Captain America, Batman...the list goes on and on.
Of course, not every great comic book character originated on the page.
In fact, some of the most iconic Marvel and DC Comics characters first appeared either on television, film, or even radio. While they first showed up there, though, it's often the comics that have put them on the map and turned them into the beloved characters they are today. However, without their non-comic book roots, they would have never existed.
That's what makes the heroes and villains here so special; after debuting in the most unexpected of places, they went on to join those listed above as household names and legit fan favourites...
10. X-23
Laura Kinney debuted in the short-lived X-Men: Evolution in 2003, and was created by writer Craig Kyle.
Just one year later, she appeared in the NYX comic book series, while Kyle and Christopher Yost would later script X-23: Innocence Lost, a six-issue miniseries detailing the character's origin in the Marvel Universe. Wolverine's clone then became part of the core franchise with Uncanny X-Men #450, and her popularity has continued to grow.
Since then, X-23 has even taken over the mantle of Wolverine, and made her live-action debut in James Mangold's Logan where she was played by Dafne Keen.
As you'll soon learn, many great female comic book characters were created for television.
9. The Wonder Twins
Despite being two of DC's goofier heroes, the Wonder Twins have plenty of fans.
They've made only sporadic appearances in the comic books in recent years, though were made an official part of DC Universe continuity in 2019. They've since shown up in titles like Action Comics and Young Justice, but may be best known for their television appearances.
If they had an IMDB page, it would make for impressive reading as they've been spotted in everything from Justice League Unlimited to The Flash.
That's appropriate as their debut came in the Hanna-Barbera cartoon, The All-New Superhero Hour, in the 1970s.
8. Jimmy Olsen
Superman's best pal, Jimmy Olsen has become a mainstay of the Man of Steel's adventures. Well, unless you're Zack Snyder and turn him into a C.I.A. agent who gets shot in the head after five minutes of screentime!
Despite having a history that stretches back to some of Superman's earliest stories, Olsen's origins are rooted in the radio show, The Adventures of Superman on April 15, 1940, in the episode "Donelli's Protection Racket." Shortly after, Jimmy made the leap to the page in Superman #13.
The character also made an anonymous cameo in Action Comics #6, and while that predates the radio show, he wasn't given a personality until he "debuted" there.
Without that, Supes would be without one of his closest allies.
7. H.E.R.B.I.E
Conceived for The New Fantastic Four animated series in the late 1970s, H.E.R.B.I.E. unbelievably replaced the Human Torch in that show when rights issues surrounding the Human Torch left him on the shelf.
Mister Fantastic, Invisible Woman, The Thing, and H.E.R.B.I.E. doesn't quite have the same right to it, huh?
It was Stan Lee who pitched replacing the Torch with a robot, and Uncanny X-Men artist Dave Cockrum was assigned to design him. When he dropped out, Jack Kirby took over, and that ended up being his final work for Marvel Comics. In 1979, H.E.R.B.I.E. made his comic book debut in Fantastic Four #209.
He's since become a fan favourite, and retained that classic Kirby-inspired appearance.
6. Mercy Graves
In the early days of Marvel and DC, most female characters were love interests or damsels in distress. It's no wonder then that so many of the great ones have debuted elsewhere.
Superman: The Animated Series isn't quite as fondly remembered as Batman: The Animated Series, but it gave us Mercy Graves, Lex Luthor's formidable bodyguard and chauffeur. Her first comic book appearance came that same year in the pages of Superman Adventures #1.
She's since been key to many of the Man of Steel's adventures involving Luthor, and has most memorably appeared in Batman v Superman: Dawn of Justice and The CW's Supergirl.
Mercy most recently appeared in Titans where she was played by Natalie Gumede.
5. Batman Beyond
Stick the Batman logo on anything, and it will probably be a hit.
However, there's something special about Terry McGinnis. Introduced as a means of picking up where Batman: The Animated Series left off, the Batman Beyond only ran from 1999 to 2001, and was put on hold for Warner Bros. Animation to instead focus on the Justice League animated series.
Despite a lukewarm reception at the time, the show would go on to gain a cult following, and found his way into the comics the same year his show debuted.
He's since appeared across the DC Universe on multiple occasions, including in a recent follow-up to the TV show which ran between 2016 - 2020. We're not fully sure why he's yet to appear in live-action, though.
4. Nova Fries
Batman fans have a lot of reasons to be grateful for Batman: The Animated Series, and it deserves a lot of credit for transforming Mr. Freeze into the complex villain we know and hate today.
Used in the show to explain Freeze's evil nature, the character was even used in the Batman & Robin film, and has been seen in both Gotham and CWVerse crossover event Elseworlds. Nora has also factored into all recent retellings of Freeze's origin in the comics (and Arkham computer games).
Her first comic appearance came in Batman: Mr. Freeze in 1997.
She's been through a lot since then including, believe it or not, becoming Mrs. Freeze last year!
3. Agent Coulson
Clark Gregg first played Agent Coulson in 2008's Iron Man where he was included only to tease the existence of S.H.I.E.L.D. and set the stage for that memorable stinger introducing Samuel L. Jackson's Nick Fury.
Despite not having any roots in the comics, he became an integral part of the Marvel Cinematic Universe, and it really stung when he died at the hands of Loki in Marvel's The Avengers. Marvel Television resurrected him for seven seasons of Agents of S.H.I.E.L.D. on ABC, however.
He first showed up as Cheese in 2011's Battle Scars #1, and was revealed as Phil Coulson in issue #6.
The comic book version didn't really resonate with fans, but Coulson remains a major fan favorite online.
2. Firestar
Debuting in 1981 on the NBC animated television series, Spider-Man and His Amazing Friends as Fire-Star, the character's popularity meant it wasn't long before she was added to the comics.
Funnily enough, her debut came in Spider-Man and His Amazing Friends #1, but Firestar is now better known for her mutant background. Since being introduced, she's been an Avenger, an X-Men, and even a member of the New Warriors.
Firestar's association with Spider-Man is why she's so fondly remembered, however, and it would be undeniably spectacular to see them one day share the screen.
It's even rumored that Firestar is going to be brought to the Marvel Cinematic Universe.
1. Harley Quinn
Now one of DC's most popular characters in any medium, Harley Quinn has grown to become so much more than just The Joker's accomplice and bit on the side!
Introduced in Batman: The Animated Series episode "Joker's Favor," the Maiden of Mischief immediately resonated with fans thanks to her complex origin story, unique appearance and demeanour, and the incredible work of Paul Dini and Bruce Timm.
Harley made the leap to comics in 1993 in The Batman Adventures #12.
Since becoming more of an anti-hero than villain, Harley's popularity has, in some ways, eclipsed that of The Joker, and she's proof that not every classic character has to debut in the comics.