Jin

First Appearance: Cyberbots: Fullmetal Madness (Sega Saturn)

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

First Appearance: The X-Men #12 

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

First Appearance: Street Fighter

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

First Appearance: Street Fighter II 

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

First Appearance: The X-Men #1 

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.   

Marrow

First Appearance: Cable #15 

From the school of character design called "lets make a new Wolverine," Marrow was one of the more popular grumpy badasses with sharp fighting utensils to join the X-Men. With an enhanced healing ability, Marrow's main power is to quickly grow extra bone mass, be they swords from her back, armor or spikes thrown at enemies. Though only on the X-men a short time, it was revealed she has two hearts and that her other identity dated Peter Parker. Not bad for a freak.   

Mega Man

First Appearance: Mega Man (NES)

Featured in more games than just about anyone not named Mario, Mega Man is Capcom's biggest star and is currently enjoying a comeback. Built around the simple but ingenious idea of copying his enemies attacks, the robot built to be a boy but forced by circumstances to battle Dr. Wily and his Robot Masters is one of the greatest heroes of our time. No matter what he's facing he always keeps a cheery demeanor, but has his Mega Buster ready just in case.   

Morrigan

First Appearance: Darkstalkers (Arcade) 

Morrigan is probably the most well-known character of the Darkstalkers franchise. A bit of royalty, she was born incredibly powerful, so her father locked away part of her power, which she would only receive upon his death. Even after his death and with the throne hers, she would much rather dabble in the world of humans. Not only magically powerful, Morrigan also has the power to transform her bat wings into any number of things, both offensive and defensive.