Iron Man

Anthony "Tony" Stark was born with extreme intelligence. After the death of his parents when he was 21, Stark inherited Stark Enterprises. After being wounded in war, he built an armored suit that would help keep him alive. Stark helped to organize the super hero team, the Avengers early in his career as a superhero.
Originally, Tony Stark had no powers of his own, and he depended on his armored suit for all of his super abilities. In it, he can fly and can shoot blasts of energy from his hands. He can also connect to various communications systems such as satellites, cell phones, and computers throughout the world. The armor has boosted his reaction time and enhanced his ability to heal.

Wolverine

While often shrouded in mystery, Wolverine's past is full of government secrets, traumatic events, and death. Born James Howlett , in rural Canada , the man who went by Logan for most of his life started out as a sickly child. His mutation did not present itself until he witnessed a violent death, and was forced to flee his home and live on the road due to the claws made of bone that sometimes protrude from between his knuckles.
For a time, he lived amongst the beasts of the wilderness, before making his way to Japan during World War II. While there, he learned the ways of the Samurai to help calm his berserker rage, before another violent death triggered his return to his native country and the black ops program of Weapon X. There, they grafted Adamantium to his bones, erased his memory, and continued his warrior training, turning him into their fiercest soldier and ultimate achievement.
Eventually he would meet Charles Xavier , who would befriend Logan and persuade him to join the third incarnation of the X-Men. From there, Wolverine has been in and out of many teams, drifting between his own agenda and those of leaders he believes in.
I'm the best there is at what I do, and what I do isn't nice.

Hulk

Bruce Banner was a scientist working on the gamma bomb when he noticed a young boy out on the test range. He heroically put his own body between the boy and the blast, resulting in being exposed to extreme amounts of gamma radiation. The radiation altered his DNA structure, causing him to become a giant green (sometimes grey) monster whenever he became angry.
His sometimes girlfriend,Betty Ross, seems to be the only thing to calm the Hulk back into Banner form, and he is often pursued by her father,General Thunderbolt Ross , to stop the Hulk from destroying things and killing people, eventually hoping to bring the Hulk to justice or destroy him altogether. Because of this, Bruce is often on the run, trying to find a cure for his problem and keep calm as much as he can.

Spiderman

Peter Parker was bitten by a radioactive spider as a teenager. The spider's DNA combined with his own giving him powers similar to that of the arachnid. He was soon able to walk on walls, shoot webbing from his arms, lift more than his own weight, and use a sense of danger as some spiders do. Upon the death of his Uncle Ben , Peter decided that 'With Great Power comes Great Responsibility', and thus took on the name Spider-Man.
He lives with his Aunt May in Queens and is usually in love with Mary Jane , (though he's dated quite a few ladies over the years). He is friends with many heroes and has a rogue's gallery that is larger than most of theirs. If an arch-nemesis would be named for Spider-Man, it'd arguably be The Green Goblin (Norman Osbourne) , who has manipulated Peter's life in so many diabolical ways over the years, Norman could be considered a Criminal Mastermind.
Always the underdog, Peter is routinely out-manned and out-gunned, but still manages to throw in the wise cracks between punches, and usually comes out on top in the end.