The Superhero genre makes up almost the entire output of action films these days, and it's hard to go to the movies or turn on the TV without seeing some sort of comic book TV show. With all the superhero media out these days, some might assume these movies and TV shows are the first times that heroes have shown up on screen. Of course, we all know about the older Batman and Superman shows and movies, but some of them are less obvious. For example, before there was a Supergirl TV show, Laura Vandervoort portrayed the character on Smallville and there was that oft-overlooked standalone movie! And that's just one example.

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It's actually pretty interesting to look back and see how far back these characters' on-screen careers go and how their depictions have changed over the years. There have been quite a few short-lived and/or obscure superhero TV shows, or just recent ones you forgot featured a now-famous comic book character. Everything from the original Incredible Hulk TV show to the forgotten Superboy series and later Birds of Prey and Smallville; all of these have had some of your favorite characters on them before their modern on-screen appearances. With that in mind, get ready for a very special history lesson.

15 GREEN ARROW

Some of you might actually remember this one, but for those who don't, allow us to take you back in time. Before CW had Arrow or any of its spinoffs, there was Smallville, a show following the life of a young Clark Kent before he started wearing a cape. Smallville might not have been the best show, but it can definitely be credited with laying down the formula for most modern CW superhero shows.

While Smallville focused mainly on Clark Kent, there were plenty of other DC characters that showed up, including the first and only live action appearance of Bart Allen, and the live action premier of Oliver Queen. The character, much like his future interpretation on Arrow, was a bit of an amalgam of Green Arrow and Batman, with some anti-hero elements thrown in. Justin Hartley portrayed Oliver, first as a recurring character, then as a series regular.

14 HARLEY QUINN

Harley Quinn is one of the few DC characters (along with Jimmy Olsen) to have an origin outside of comics. Bruce Timm and Paul Dini created her to be a henchwoman for The Joker on Batman The Animated Series and she eventually found her way to comics. Perhaps since she was an animated character first is the reason why she hasn't had many live-action appearances.

This isn't to say she's been absent from live action, since 2016's Suicide Squad featured Margot Robbie as the character. However, before this, her appearances are rather sparse. Besides a cameo on Arrow (where she couldn't even be credited as Harley Quinn) the Joker's #1 gal only had one other live action appearance. On the short-lived Birds of Prey, Mia Sara portrays Dr. Harleen Quinzel, a deranged psychologist who plans to take over Gotham by stealing meta human superpowers.

13 SPIDER-MAN

Before there was Holland or Garfield or even Maguire, there was a whole slew of Spider-Man TV actors. It all started in 1974 with recurring skits that appeared on The Electric Company, where Spider-Man was portrayed by Puppeteer and dancer Danny Seagren. The skits were used to teach kids lessons and help them develop reading skills by having Spidey speak only through on-screen word balloons.

Later in 1977, Nicholas Hammond played Spider-Man in a TV-movie-turned-series titled The Amazing Spider-Man. The show only ran for two seasons and concluded in 1979. Strangely enough, right around the same time, Japan and the Toei company ran their tonkusatsu Spidey show, simply titled Spider-Man. Shinji Todō played the titular character, though the interpretation had very little to do with the Marvel character, incorporating strange elements (like a giant fighting robot) to draw in young male audiences.

12 AQUAMAN

Jason Mamoa's portrayal of Aquaman might not be out yet, but it's not the character's first live-action appearance; in fact, there have been two others. The first comes from, surprise, Smallville, where he was played by former American Idol contestant, Alan Ritchson (fingers crossed for an Aquaman musical). Ritchson played the character for a total four episodes across various seasons and even reprised the role in the animated movie, Justice League: The New Frontier. Aquaman shows up in season 10 alongside his new wife, Mera (portrayed by Elena Satine), who teaches him of his Atlantean origins.

In 2006, the CW turned down a live action Aquaman series, but a pilot had been filmed. Strangely enough, the titular character was played by Smallville Oliver Queen actor Justin Hartley. Though the show didn't get picked up, the pilot is still available through various digital distributors.

11 CYBORG

Though he didn't take up the name "Cyborg" until his second appearance, Victor Stone's first live-action portrayal was in Smallville (man, there are a lot of these!). The character was played by the late Lee Thomspon Young for three episodes in seasons five, six and nine. This version of Cyborg didn't have his cybernetic parts showing, the bionic components keeping him alive being under his skin instead.

Smallville's Cyborg also has a slightly different origin. Victor is still a former football player who was involved in a car accident, but his "resurrection" is actually the result of corporate experimentation, rather than his father saving his life. Cyborg's second appearance was in the episodes titled "Justice," in which Green Arrow recruits him for a team along with Impulse, Aquaman and Clark Kent. In his final appearance, Cyborg helps fight against the Kandorians in the season nine episode "Salvation."

10 DAREDEVIL

While we all love Charlie Cox as Matt Murdock on Netflix and Marvel's Daredevil, it wasn't the first time the man without fear was featured on screen. No, we're not talking about Ben Affleck in the critically panned Daredevil film, we're talking about The Trial of the Incredible Hulk. This was the second of three televisions-film continuations of the original Incredible Hulk TV series and was directed by Bruce Banner himself, Bill Bixby.

After Banner is arrested for a crime he didn't commit, Matt Murdock is assigned to his case. Matt later reveals to Banner and The Hulk that he is Daredevil, the vigilante who protects the city from Wilson Fisk's rule. The film was a failed attempt to spin off a Daredevil TV show, though the costume Daredevil wore was the basis for both Frank Miller's The Man Without Fear, and the later Netflix series.

9 GREEN LANTERN AND SINESTRO

Back in 1979, there were two strange hour-long specials that premiered on NBC. The specials were produced by Hanna Barbera and based on their Super Friends Cartoon. Titled Legends of the Superheroes and filmed like a variety show (laugh tracks and all), these two specials brought together famous superheroes for the first time on live-action television.

The first episode follows the Justice League as they try to stop the Legion of Doom's evil plot, which is a trap to de-power the heroes. Amongst the various superheroes and villains are Green Lantern Hal Jordan and his archenemy, Sinestro. Howard Murphy played Hal and comedian Charlie Callas portrayed Sinestro. This strange special premiered a good 32 years before the characters were portrayed by Ryan Reynolds and Mark Strong in the failed live-action Green Lantern film.

8 BLACK CANARY AND HUNTRESS

Legends of the Superheroes featured a lot more DC characters than just Green Lantern. In fact, the show was also a bit of a reunion for three Batman '66 actors, as Adam West, Burt Ward and Frank Gorshin returned for their roles of Batman, Robin and The Riddler. Amongst the other heroes were two of the Birds of Prey themselves, Black Canary and Huntress, played by Danulta Wesley and Barbara Joyce.

This wasn't the two heroes only live-action appearance before their depictions on Arrow, as they were two of the three leads from the short-lived Birds of PreyRachel Skarsten played Dinah Redmond, a telekinetic metahuman who was the daughter of the original Black Canary while Ashley Scott played Helena Wayne, daughter of Bruce Wayne and Catwoman. Black Canary also showed up in Smallville, portrayed by Alaina Huffman before both characters were on Arrow.

7 THOR

Preceding Daredevil's appearance in The Trial of the Incredible Hulk, there was the first Incredible Hulk follow up TV movie, The Incredible Hulk Returns. In it, the mighty Thor himself shows up, sort of. Instead of Thor being banished from Asgard and forced to live as a human, this version was Donald Blake, a mountaineer and former student of Banner who turned into Thor after finding his hammer in a mountain cave. Donald Blake was played by Steve Levitt and the god of thunder was played by Eric Allan Kramer.

The two powerful heroes fought, as they are wont to do, before coming to a standstill and working together. This dual-identity version of Thor was chosen to give common ground between Thor and Hulk, as he and Blake are fighting over control of his body, which is why he seeks Banner's help.

6 SHAZAM

It was just recently announced that Shazam would be the next DCEU film to go into production, so we thought it'd be cool to look back in time at Shazam/Captain Marvel's other live action appearances. The first, and perhaps more well-known is of course the live action Shazam series. Tweaking the lore a bit, the show followed Billy Batson and his mentor (simply known as Mentor) as they travelled across the country in a motorhome helping those in need by transforming into Captain Marvel.

Billy was played by Michael Gray and Captain Marvel was first played by Justice Bostwick and later John Davey. The show ended after three years on CBS, but it wasn't the last time the character showed up on TV. Once again Legends of the Superheroes comes up, as the character was played by Garrett Craig on both episodes of the special.

5 MARTIAN MANHUNTER

Though there are no plans as of yet to include Martian Manhunter in the DCEU, he does have a recurring role on Supergirl, along with his niece Miss Martian. However, this isn't the first time J'onn J'onzz showed up on live action TV. There were actually two instances where everyone's favorite martian had a live action portrayal. The first time was the obscure, failed Justice League of America TV pilot. David Ogden Stier portrayed Martian Manhunter who only seemed to have shapeshifting abilities, ones that only worked for a short period of time at that.

Manhunter's second appearance was, of course, on Smallville, where he almost exclusively appeared in disguise as John Jones. Phil Morris — who you might know as fast-talking Lawyer Jackie Chiles from Seinfeld — played the character, only showing his Martian form in a few instances.

4 SLADE WILSON

Bet you're wondering why we specifically said "Slade Wilson" instead of "Deathstroke," huh? Well, there are two reasons. For one, there was a Deathstroke on TV before Arrow, but the only thing he had in common with the comics version was that he was an assassin. This version of Deathstroke showed up on Lois and Clark, played by Antonio Sabàto Jr, and had magnetism powers instead of a healing factor. His real name wasn't even Slade Wilson, it was Earl Gregg.

The other Slade Wilson to show up didn't even take up the name Deathstroke. On (here we go again) Smallville, Michael Hogan portrays an older Slade Wilson, a united States Army Lieutenant General who spearheads an anti-vigilante movement. After losing his eye and gaining healing abilities, Wilson spouts the unbelievable cheesy line, "I am beyond Death's stroke now." Man, thank goodness for Manu Bennett.

3 THE ATOM

It makes sense that a guy who can shrink has had such small roles on TV... Anyway, people might know Ray Palmer, aka The Atom, as Brandon Routh on Legends of Tomorrow, but this wasn't his first appearance on live-action television. Yet again, we find the first appearance of a hero to be on Legends of the Superheroes. The Atom's first and now his most recent TV show appearance both have "Legends" in the title.

However, there was one more live action Atom portrayal before Arrow and Legends: the Justice League of America pilot. The Pilot had a rather strange league lineup including Martian Manhunter, Fire, Ice, Guy Gardner, The Flash and The Atom. John Kassir, known for voicing the Crypt Keeper of Tales from the Crypt, portrayed Ray Palmer in the pilot.

2 METALLO

Some might not remember that Metallo was on Smallville, since a lot of viewers dropped off by the time season nine rolled around. Brian Austin Green portrayed the character on the CW series, but he wasn't the first actor to take the role. The 1988 Superboy TV series featured a wide variety of Superman characters and was, in many ways, the Smallville of its time. Of the various characters that showed up, Metallo terrorized Superboy for several episodes. In it, he was portrayed by Michael Callan with his origin story shown in his first episode.

A year after Superboy ended, Lois & Clark took its place, featuring Dean Cain and Terri Hatcher in the titular roles. The show also featured a version of the radioactive robot. In the episode titled "Metallo," Scott Valentine played Metallo, a petty criminal who had his scientists brother rebuild him as a kryptonite-powered cyborg.

1 BIZARRO

So far, there have only been two portrayals of Bizarro in live-action DC television, well, maybe two and a half. The most recent version was on Smallville, portrayed in a dual role by Tom Welling, but there was one before that on the Superboy series. Bizarro shows up in seven episodes of Superboy played by Barry Meyers. This version of Bizarro is like his silver-age interpretation where his criminal acts are actually him just lashing out at being deemed a freak by society.

Though this is the only official version of Bizarro on TV before Smallville, there is one episode of Lois & Clark we can consider, too. In the episode "Vatman" from the first season, Lex Luthor creates a clone of Superman that was made to kill him. Eventually, Superman convinces his clone to side with him, only for him to disintegrate soon after.

Can you think of any other heroes who showed up before they found fame on modern TV? Let us know in the comments!