From the DC Animated Universe to the Marvel Cinematic Universe and everywhere in-between, we've been treated to some fantastic original characters who we not in the original source material, but were created specifically for their specific adaption. In fact, many of these characters have gained such popularity that most fans might not even realize they aren't from the comics. Below I've gathered up my personal favorites. Some of these characters were used in an adaption of a comic and then were never seen again, but some have gone on to transcend mediums and crossover between live-action adaptions and the comics that inspired them.
#10 - Jemma Simmons (Marvel's Agents Of S.H.I.E.L.D)
One of the newest characters on this list. I gotta admit, like many people, I was hesitant to embrace Agents Of SHIELD when it first premiered. In the first half of the show's freshman season there was a lot of dragging along and at times I felt my interest weaning. But one of the few elements I really enjoyed was Jemma Simmons, a younger SHIELD agent and scientist in the series. She didn't really do much at first, often only being there to provide comic banter with Fitz, but after a few episode she began to grow as a character and was given a bit of depth. She's proven to be loyal to her team and has even gone to great lengths to protect them (even throwing herself from a plane because she didn't want to endanger them). She's one of the highlights of the series and I'm looking forward to seeing her character grow even farther.
#9 – Renee Montoya (Batman: The Animated Series)
Renee Montoya was originally introduced in Batman: The Animated Series during season one and continued to be a recurring character in season two. Since her initial appearance she's gone on to transcend her medium, appearing in the actual DC Comic Universe. She's even gone from being a police officer to becoming The Question, a vigilante who wears a mask that creates the illusion of the wearer not having a face.
#8 – X-32 (X-Men Evolution)
X-23 was originally created for the animated series 'X-Men: Evolution”. Another character who has transcended her original medium, X-23 was created from DNA of the original Wolverine and therefore share similar abilities (most notably: her claws). She was used as a killing machine for many years before finding Wolverine and the other X-Men and deciding to turn her life around.
#7 – Firestar (Spider-Man And His Amazing Friends)
Firestar was originally created for the animated TV series 'Spider-Man And His Amazing Friends' where she fought the forces of evil alongside Spider-Man and Bobby Drake, aka Iceman from the X-Men. Firestar has gone to appear in various comics and while she's somewhat popular, she never really gained the mainstream popularity that various others on this list have.
#6 & #5 – Bebop and Rocksteady (Teenage Mutant Ninja Turtles)
Bebop and Rocksteady were originally introduced in the original 'Teenage Mutant Ninja Turtles' cartoon series and have since gone on to appear in comics published by IDW. Bebop and Rocksteady have proven popular with fans. Despite being generally well-liked character, Bebop and Rocksteady did not appear in the 2003 'TMNT' series (except for the Turtles Forever crossover movie), they were not used in any of three live-action films and have yet to appear in the 2013 series on Nick.
#4 – Merle Dixon (The Walking Dead)
Say what you want about 'The Walking Dead', but there is no denying that Merle Dixon was a cool character. I mean, c'mon! It's Micheal Rooker with a knife for a hand. How can you not like that? Merle was a character that, at first, didn't seem to have much going on. However when he returned in season three, he proved to be a complex character and while he never appeared in the comics (and likely never will), he is still one of my favorite characters in the Walking Dead universe, TV or Comic.
#3 – Terry McGinnis/Batman (Batman Beyond)
Terry McGinnis was originally a troubled teenager that was taken under the wing of an elderly Bruce Wayne and taught the ways of crime fighting in the series 'Batman Beyond'...By the end of the DCAU, it turned out he was a weird test-tube baby of Bruce Wayne or something...I dunno, it was complex. I like to focus on everything before that though. The series had a fun vibe of Spider-Man meets Batman and it made the entire thing very enjoyable.
#2 – Phil Coulson (Iron Man, The MCU)
The Son Of Coul. Phil Coulson started in the movies, appearing in nearly every MCU movie leading up to 'The Avengers'. Since then he's gone on to appear in the comics and on TV in an animated series and in a live-action TV of series, of which he is the primary character. Phil Coulson is a prime example of introducing an original character right. In less than 7 years, he's gone from a fun cameo-type character in Iron Man to the glue of the entire MCU.
#1 – Harley Quinn (Batman: The Animated Series)
Harley Quinn is another prime example of properly introducing an original character. Originally created as a fun girlfriend-character for the Joker, Harley has gone on to gather her own fan-base that is large enough to rival some A-List comic characters. Pick up a Batman comics and you'll probably see a reference to her. Go to a Comic Convention and you'll probably see a dozen women dressed as her (it's probably the second most popular female costume behind the Slave Leia outfit). She's been around for years and her popularity hasn't dropped off any. She remains an interesting an beloved character and has proven to stand the test of time and for that reason, Harley Quinn is #1 on my list.
HONORABLE MENTIONS:
Jimmy Olsen (The Adventures Of Superman Radio Show), Mercy Graves (Superman: The Animated Series), Agent Melinda May (Marvel's Agents Of SHIELD), Phantasm (Batman: Mask Of The Phantasm), Daryl Dixon (The Walking Dead), Blight (Batman Beyond), Chloe Sullivan (Smallville), Livewire (Superman: The Animated Series), Agent Grant Ward (Marvel's Agents Of SHIELD), Red X (Teen Titans)