Agent Phil Coulson, 'The Avengers' films
Considering he's one of the Marvel cinematic universe's most well known and beloved characters besides the heroes themselves, it may shock you to learn that prior to the first Iron Man film, there was no Agent Coulson. In fact, he was not introduced into the comics until 2012, in a miniseries called Battle Scars (Side note: coincidentally, this storyline also premiered Nick Fury, Jr., a character resembling Samuel L. Jackson's Nick Fury from the films. In the comics, the Nick Fury character is Caucasian). Agent Coulson has since played a prominent role in the Secret Avengers comic book series.
Harley Quinn, 'Batman: The Animated Series' (1992)
Even those who are incredibly unfamiliar with comic books will surely recognize Harley Quinn, The Joker's main squeeze from the 1992 Batman animated series. Believe it or not, this extremely popular character got her start on the children's show, never being officially adapted into DC Comics' canon until 1999's Batman: Harley Quinn. She's since been adapted into the New 52 version of DC Comics in both the Suicide Squad series, as well as her own monthly book. Batman: The Animate Series was also responsible for eventual comic book counterparts Renee Montoya and villain, Lock-Up.
Terry McGinnis, 'Batman Beyond' (1999)
Okay, it's one thing to introduce a new Batman villain or side character in a cartoon. That's to be expected considering cartoons are for children, and many comic book characters might be considered too dark for them. However, Batman Beyond was a rare case. It spun off from the original Batman: TAS and followed Terry McGinnis, a teenager who takes on the role of Batman in the not too distant future under the tutelage of an elderly Bruce Wayne. While Terry has made appearances in comic books that continue with the animated series' continuity, he was never introduced into actual DC Comics until it was recently announced that he would finally get his moment in the spotlight in the The New 52: Futures End comic book series.
Morph, 'X-Men: The Animated Series' (1992)
Here's one so complicated and involved, we don't even know where to begin. Although the character of Morph, a shape-shifting mutant introduced and killed in the pilot episode of the '90s X-Men cartoon, was loosely based on a character named Changeling briefly introduced and killed in the X-Men comics of the '60s, the two are considered separate entities due to vastly different personalities. However, the Morph of the TV series was eventually resurrected. His original comic book inspiration was, too, but that version was then modeled much more after the TV version in terms of his humorous personality. He was even renamed Morph along the way. Why include another shape-shifting character at all when they had the much more popular Mystique, we'll never know. It'd be like making another Wolverine for no reason.
X-23, 'X-Men: Evolution' (2000)
Ahh, that last slide segued perfectly into X-23, aka, another Wolverine for no reason. Yes, X-23 is a mysterious character with the retractable claws of Wolverine, only she merely has two on each hand (as well as one on each foot). Oh, and most importantly, she debuted on the TV series X-Men: Evolution as a female clone of the iconic X-Man. She would eventually be adapted into the comics via limited series NYX, in which she was portrayed as a homeless prostitute living in New York City before she was eventually fleshed out more and given star status in books such as Avengers Arena and even her own ongoing series.
Jimmy Olsen, 'The Adventures of Superman' (1940)
You'd think Jimmy Olsen, the not-so-interesting protege to Clark Kent and Lois Lane, would have a not-so-interesting origin. After all, they could never manage to make him very engaging in the comics no matter how hard they tried. But in fact, his story is perhaps the most interesting of all when it comes to this particular subject matter. Otherwise, he's still a dud. You see, Jimmy was actually first introduced not on television or in movies, but on the radio. The Adventures of Superman radio show debuted in 1940, a year before Jimmy was officially introduced in the comics (although an unnamed copy boy whom people believe to be Jimmy was seen in the pages of Action Comics in 1938), and he was added to the show as someone for Superman to talk to on his various adventures. Perry White was also first introduced on the radio series. Similarly, Chloe Sullivan, Jimmy's eventual girlfriend on the TV series Smallville, was an original character to that series before transitioning into the pages of the comics.
The Green Hornet, 'The Green Hornet' (1936)
What do Jimmy Olsen and the Green Hornet have in common, you ask? Well, considering the previous slide, the answer to that riddle is probably pretty obvious. While many believe that the Green Hornet made his debut in comics, he was actually first heard over the radio airwaves of a local Detroit station on January 31, 1936. He never made it into comic book form for another five years or so. But don't worry, as long as you didn't think Seth Rogen created the character, you're still in good shape.
Bebop & Rocksteady, 'Teenage Mutant Ninja Turtles' cartoon (1987)
While the '80s Ninja Turtles TV series introduced a slew of characters who weren't from the comics, it was inept henchmen Bebop and Rocksteady who stood out the most. They, along with characters such as Krang, who was also a TV series original, would eventually make their way into official Ninja Turtle comic books, even spawning their very own micro-series. Unfortunately, Tokka & Rahzar from Teenage Mutant Ninja Turtles II: The Secret of the Ooze (1991) have yet to see the light of comic book canon.
Daryl & Merle Dixon, 'The Walking Dead'
This one is a bit of a cheat, as while both Daryl and Merle Dixon have played very prominent roles on The Walking Dead TV series, they have yet to transition over to the comic book at all. In 2012, there was much speculation that issue #101 of the comic series would finally feature an appearance from at least Daryl due to this incredibly leading cover (pictured). Sadly, this proved not the case. But due to the longevity of the comic and the inevitable death of Daryl (R.I.P. Merle) on the TV series, we have to imagine his popularity will spur a rebirth of sorts in print form sooner than later.
Abraham Whistler, 'Spider-Man: The Animated Series' (1994), 'Blade' films and animated series
Last but not least, we end on yet another character who was given life on not only the small screen, but more famously, in three films as well. Abraham Whistler, mentor to vampire hunter and daywalker, Blade, was first seen on the popular '90s cartoon Spider-Man, even though he was originally created by none other than famous screenwriter David S. Goyer. Goyer would later write him into his Blade trilogy. Much like the Morph character we mentioned earlier, Whistler was loosely based on a previous Blade comics character named Jamal Afari, who similarly watched over Blade after discovering his unique gifts. The big difference here is that the Whistler character, much like the Dixon brothers, has yet to cross over. But we figure with the Blade series prime for a reboot, it is only a matter of time.