Injustice proved to be a smash hit when it released in 2013. The title delivered the kind of match ups that DC Comic fans had always dreamed of, while at the same time offering a surprisingly entertaining story of a Superman pushed too far. It's little surprise then that a sequel is on the way, and so far it looks to be every bit as fun as the first.

That being said, a fighting game is only as good as its roster, and Injustice 2's lineup of superheroes and superviallins is still largely a mystery. Reveal footage of the game shows fans will be able to play as first time Injustice characters Gorilla Grodd, Atrocitus and Supergirl, with characters like Batman and Aquaman also making a return from the first game. But what other new characters can fans expect? An Injustice 2 t-shirt being given away during E3 week seemed to tease that characters like Captain Cold, Doctor Fate and others would be joining the roster this time around, but as of yet the game's roster is largely unconfirmed.

Thankfully, that leaves the door open for plenty of surprise appearances. Mortal Kombat creator and NetherRealm head Ed Boon has already been polling fans on Twitter about what characters they would like to see in the game.

No doubt choosing who to include is harder than one might think. With the entire DC universe at NetherRealm's fingertips, narrowing down the cast of characters to two dozen or so fighters is no small feat. Good thing we have some suggestions. Here are nine characters NetherRealm should consider for Injustice 2.

Beast Boy

The green Teen Titan's ability to shape into various animals seems simply too cool of an opportunity for NetherRealm to pass up. Whether it be transforming into an elephant to stampede over foes or swoop down onto enemies as a bird of prey, Beast Boy's moveset could be one of the most diverse and visually entertaining characters in the game. Plus, he can change into a T-Rex. Who doesn't want a T-Rex finishing move?

Swamp Thing

Swamp Thing, a supernatural protector of the environment, seems like a perfect fit for Injustice's grim alternate universe. He even played a minor role in the Injustice comic series. With his power to regenerate and control plant life, the creature of the swamp would make a formidable opponent. The character ranked second in one of Boon's recent Twitter polls, so perhaps Swamp Thing is already in development.

Red Tornado

Technically Red Tornado has been MIA for a couple of years now (thanks New 52), but he's still a major character that fans who grew up watching the Justice League animated series, or more recently Young Justice, are familiar with. He's even in Supergirl. His ability to create superpowered winds and his android nature is a unique combination that would no doubt make for an interesting moveset.

Grail

The daughter of Darkseid is one of DC's new big bad villains on the block. The exact plot of Injustice 2 is still unknown, but if Darkseid is somehow involved, it only seems natural for his badass daughter to make an appearance.

Constantine

The magically powered detective with an extensive knowledge of the occult is yet another anti-hero would would feel right at home in the Injustice universe. In fact, he was already featured prominently in the Injustice: Year Three comic book storyline, where he fought with Batman against Superman, using his magic know-how to help cook up battle plans against the Kryptonian dictator. Constantine's mixture of brains, magic and ne'er-do-well attitude would fit right in.

Blue Beetle

Blue Beetle isn't typically regarded as one of DC's heavy hitters, but he's seen a rise in popularity as of late thanks to Young Justice and a New 52 era comic series. He even won Boon's recent Twitter poll of characters fans most want to see, beating out both Captain Cold and Swamp Thing. With that in mind, perhaps his inclusion is all but inevitable, but we're still going to go on record and cast a vote for the hero to appear regardless.

Poison Ivy

Batman's rogues gallery is one of the best in comics, so it would be a shame if Injustice 2 didn't highlight some of them. Joker, Harley Quinn, Bane, Catwoman and Solomon Grundy all appeared in the original game, so it's time for some new Gotham City villains to take the stage. We can't think of a better candidate than Poison Ivy. Aside from adding some much needed diversity to the game's roster. her plant powers could make for a potent fighting style.

Static

Fan favorite hero Static is actually already a character in the Injustice mobile game, but never made it into the console game proper. That makes it high time for the electricity wielding Teen Titan to join the big leagues in Injustice 2. Many fans know the character from his 2000 animated series Static Shock, but he recently appeared in the popular Young Justice series as well. Work on a live-action Static show is even in the works, making it the perfect time for Static to step into the spotlight.

Clayface

Yet another iconic Batman villain, Clayface's morphing abilities alone make him a strong candidate for Injustice 2. The game is already looking great, and NetherRealm could certainly have a lot of fun bringing Clayface's grotesque, shifting appearance to life on current generation consoles.

The DC universe is a huge place, filled with hundreds upon hundreds of characters. These are just a few candidates that would be cool to see included, but ultimately the decision lies with NetherRealm Studios. No doubt we'll be hearing more about Injustice 2, and the game's roster, in the months ahead, so here's hoping some of our picks make the cut. Which characters would you like to see included? Let us know in the comments below.