Hayato
Known as the main character of Capcom's first 3D fighter, Hayato Kanzaki and the lightsaber rip-off he wields have been largely forgotten. Taking place in 2348, Hayato is out to save the orphanage he grew up in - and the planet that it's on - from the evil, Nobel prize winner/cyborg Dr. Bilstein. Making the transition from 3D to 2D worked pretty well for Hayato, as MVC2 keeps him in the public eye way more than his dead series does.
Hulk
Needing little introduction, Hulk is the raging beast below the surface of innocent nerd, Bruce Banner's psyche. Created from a freak gamma bomb accident, whenever he loses control of himself, the Hulk comes out, with his limited intelligence and unlimited power. Basically Hulk is as strong as he needs to be, because if he isn't strong enough, he gets angry then gets stronger. On top of that he has an amazing healing factor and is virtually unkillable when Hulked out.
Iceman
One of the original five X-Men, Bobby Drake has the ability to create ice out of thin air by dramatically reducing the heat in the immediate area. Normally used to throw ice projectiles or make slides out of ice that he and friends travel on, his powers seem good but limited. However, it's been recently pointed out that he is one of the most powerful mutants, with powers that could inflict global climate shifts. Though his life has had ups and downs, the X-Men can always count on his loyalty.
Iron Man
Featured in a recent film you may have heard of, Iron Man is one of Marvel's top heroes. When an injury led lazy playboy and industrialist Tony Stark to make a life-saving suit of armor, Tony decided to keep on using it to help the world. Unlike most heroes, Iron Man's costume is in a constant state of flux, as improvements and alterations are continually being made, Though flight, strength and energy blasts are a given, who knows what else the cybernetics genius will add to his robo-clothes next.
Jill
One of the two main characters in the original Resident Evil, Jill Valentine is known the world over as the "master of unlocking." She's equally good with a pistol as she is with a lock-pick, taking down hundreds of Zombies as a member of S.T.A.R.S. She's sorta in the recent RE5, but we'd rather not spoil things. But despite being the enemy of the undead, one of her moves summons them to aid her in MVC2. Has the world gone topsy-turvy?
Jin
Living in a world where piloted mechs fight each other like street fighters, only bigger, Jin isn't too far from his robot, the BX-02 Blodia. In fact, you'll see its hand delivering him to his matches in MVC2. Out to avenge the death of his father like any good fighting game protagonist, Jin will get the truth one mangled mech at a time. Aside from MVC2, Jin and his mech are hidden characters in the Dreamcast classic and untapped franchise Tech Romancer.
Juggernaut
The jealous and hateful stepbrother to Charles Xavier, he's turned sibling rivalry into a deadly need to destroy Chuck's X-Men. And he can do it too, thanks to the Crimson Gem of Cyttorak, which gives him the power to be unstoppable. Literally nothing can stop him so long as can build up a slight momentum. On top of that he's incredibly strong and indestructible, incapable of even feeling pain. Because of this, the X-Men never really beat him so much as cheat him or trick him until they have to deal with him again.
Ken
One half of the main duo in Street Fighter, Ken has been around from the beginning. The American fighter trained with Ryu under Gouken and has a similar, but subtly different fighting style. The best example is that while Ryu is the master of the Hadouken, Ken is the best at the fiery uppercut Shoryuken. A well-known fighter internationally, Ken is always seen as Ryu's equal, but has much more of a social life. He eventually has a child named Mel with his wife, Guile's sister-in-law, and goes on to train a new fighter named Sean, one of Ryu's rivals in SFIII.
M. Bison
Arguably the top villain in Street Fighter, M. Bison and his terrorist organization Shadaloo have been effing stuff up for a while, until he had the silly idea of inviting the world's best fighter to face him, which they eventually used as a way to take down his empire. You wouldn't think that would happen, as Bison is crazy dangerous thanks to his Psycho Power, mainly built around electricity and flying at people. After having his body destroyed, he returns in SFIV, inhabiting a new and more powerful body, proving you can't keep a good man down.
Magneto
With the power of magnetism over any metal, Magneto is one of the most powerful and dangerous mutants on earth. A flawed villain, he is fueled by the desire to save his mutant brothers from humanity. If that means killing and subjugating humanity with mutants in charge, then so be it. Aside from being able to move skyscrapers with a wave of his hands, Magneto can also create electro-magnetic force fields around himself and can fly. He won't be happy until mutants are safe, even if he has to kill some mutants, namely the X-Men, to do it.
