It is not uncommon for Hollywood to recruit completely unknown actors to play iconic superheroes. After all, the formula worked when Christopher Reeve was given a cape and a pair of speedos to play Superman. However, standards towards superheroes nowadays have quite changed in that such a role has higher expectations from fans and as such, Hollywood is less willing to take a risk on an unknown taking on such a monumental part anymore.
However, the formula still has a history worth addressing and, in rare cases, a history that continues to be practiced by certain studios. Look no further than Mia Sara's role as Harley Quinn as a prime example of such a formula. Such a formula gave birth to big stars, while in other cases, some unknown actors stayed unknown long after they stopped filming.
10 Mia Sara - Harley Quinn
Mia Sara may not so much be an unknown actress - some fans may recall her 15 minutes of fame from playing the role of Sloan in Ferris Bueller's Day Off - as much as she is a forgotten actress, but whether you recognize her or not, there is still one thing that can never be taken away from her and it is the fact that she is the first actress to play Harley Quinn in live-action form.
The form came in the short-lived Birds of Prey series, which if you didn't see it before it got canceled, the show takes place in a world where Batman abandons Gotham and to pick up his scraps, Oracle, Huntress, and Black Canary join forces to save the city. Mia Sara pulls double duty as Huntress' therapist, Harleen Quinzel, then, of course, Harley Quinn.
9 Helen Slater - Supergirl
In 1984, to follow up the success that was Superman starring Christopher Reeve, The Powers That Be - those powers being Warner Bros. - decided it was time to freshen up the series after the second sequel by introducing a female counterpart. To play that counterpart, Helen Slater was offered the role.
Despite both Demi Moore and Brooke Shields putting their hats in the race, film rights owners Ilya and Alexander Salkind really wanted an unknown actress. With no movie credits before filming Supergirl, Slater was a shoo-in.
8 Lili Simmons - Catwoman
We could have easily filled this slot using Camren Bicondova seeing as she spent the entire series of Gotham playing Selina Kyle, but Kyle never truly became Catwoman until she reached adulthood. We never watched all of the Bat kids - Bruce Wayne included as Batman - until the series finale, taking place years after the events of the previous episodes.
To take up the task of becoming an older Catwoman, Lili Simmons was taken up to the task. Simmons has some credits to her name, but she's more of a rising actress in Hollywood who has yet to become a household name. She's on her way up the ranks, though, as this is her biggest role to date.
7 Alan Ritchson - Aquaman
Smallville boasted a few then-unknown actors in the roles of big-name heroes, including Kyle Gallner as Bart Allen and Justin Hartley as the Green Arrow. Although there were also some mildly known names in the mix, like the now late Lee Thompson Young as Cyborg, for example. But then, you have actors who never heard from before or after Smallville was on the air.
In the latter case, one of those actors was Alan Ritchson, who played Aquaman. Besides voice Raphael in the new Teenage Mutant Ninja Turtles reboot series and play Hawk on Titans, Ritchson has kept a relatively low profile since Smallville went off the air. Speaking of Titans ...
6 Brenton Thwaites - Robin/Nightwing
Pretty much the entire core cast of Titans is run by unknown actors, but for the figurehead of the team - Dick Grayson, AKA Robin, then Nightwing - to be an unknown star himself had to have been a hard sell.
With few credits to his name since making his acting debut in 2010, the closest that Brenton Thwaites had to a big role was playing the son of Will and Elizabeth Turner in Pirates of the Caribbean: Dead Men Tell No Tales. But since that performance failed to make waves for him, his performance as Robin is proving to be the breakout role he needed.
5 David Harewood - Martian Manhunter
For all of the fan castings that fans had envisioned for the Martin Manhunter, David Harewood was not at the top of anyone's list. In fact, when he joined the cast of Supergirl initially as the director of D.E.O., similar to a short-lived role he played during one season of Homeland, most fans did not expect him to be superpowered at all.
But alas, Harewood revealed himself slowly as each episode progressed as the Martian Manhunter. Even better, he wound up pulling double duty as Cyborg Superman later down the line.
4 Matt Ryan - Constantine
While not the most famous character on this list, he was always iconic enough that there was a legitimate public outcry when fans were disappointed to see that the very American, very clean cut and black haired Keanu Reeves was picked up to play the very rugged, very British blond, John Constantine.
Thankfully, Matt Ryan was able to regain fan interest in the character with his own iteration. Even better, despite his original NBC show being canceled, Ryan was so perfect in the role that he was asked to reprise it for the Arrowverse. Now, he's completely synonymous with the character.
3 John Wesley Shipp - The Flash
Long before Grant Gustin was chosen to be our Fastest Man Alive, that honor belonged to John Wesley Shipp when he starred in the 1990s The Flash as CBS' title character. As Danny Bilson explained to the LA Times, "There are 125 special effects. It's done on a grand scale." This suggests that the show was just too expensive to maintain for longer than a season.
Despite its inevitable cancelation, Shipp's Flash found a new life when he reprised the role for a multiverse version of the character in The CW's Flash series.
2 Mike Colter - Luke Cage
During his late 20's, Mike Colter joined the entertainment industry late, with his first movie credit coming in 2004's Million Dollar Baby for a small role. He had some small supporting breaks since then, but nothing to make him a memorable name and face.
That was until he was brought on by Marvel to bring the iconic comic character of Luke Cage to life for a Netflix series, along with a few spin-offs like The Defenders. He has already quickly defined our vision for the live-action version of the character.
1 Warren Christie - Batman/Bruce Wayne
The first season finale of Batwoman gave us our very first glimpse of Bruce Wayne, AKA Batman. Granted, that face was attached to Hush in disguise, but this basically confirmed that when we see the real deal unveil himself, he will be played by Warren Christie.
You may not have heard that name before and Christie does not have many memorable credits to his name, but showrunner Caroline Dries wants us to know that the cowl is in good hands. "Oh my gosh, he’s such a good actor," Dries told TV Line. "He’s been in some of the shows that I have watched, and when I saw his name come up in our casting sessions, I was like, 'Um, hello! Yes, obviously.' And then when I met him, for some reason I was holding the blueprints of the Batcave, so I was like, 'Oh, let me show you the Batcave! Here’s where this is, here’s where this is….' We were geeking out over it together."