Wade's mother died of cancer at some point in his early childhood, which left him in the care of his physically abusive father. Wade was a bit of a hardcore, rebellious, don't-do-as-you're-told kind of guy. He was left an orphan when one of his friends shot and killed his father. After a brief military career he became a mercenary for hire. In America (Wade was born and raised in Canada) he met and fell in love with this American chick called Vanessa however when he later learned he had contracted cancer he broke up with her to save her the pain of being with a dying man. But back in the snowy north of Canada he was offered a chance at survival by Department K, a special weapons development branch of the Canadian government. Wade became a guinea pig in the Weapon-X Project, you've heard of that right? Wolverine? Adamantium claws? Terrible X-Men prequels starring Wolverine? All that jazz.
Weapon-X attempted to transfer Wolverine's healing factor into Wade Wilson, effectively curing his cancer. Of course they were more interested in creating duplicate Wolverine super-soldiers than curing cancer. Unfortunately the experiment failed and Wade was left horribly scarred, as you can see in the picture to the right. He was sent to a facility for Weapon-X rejects. The facility's inmates served as subjects in sadistic experiments. The inmates would place bets in a dead pool on which inmate would die next and Wade was always at the top of the list. Wade was brought to the brink of death after having his heart ripped out however he was saved when his healing factor given to him in Weapon-X suddenly kicked him, growing him a new heart and curing his cancer. Unfortunately his new healing powers couldn't rid him of his horrible scars.
Despite being left mentally unstable from his experiences Wade managed to escape and took the name Deadpool. He began donning a red full-body suit and returned to his life of being a mercenary. Deadpool like Spider-Man became known for cracking jokes. Deadpool is the only person in the Marvel universe that is aware he is a comic book character and often breaks the fourth wall by addressing the reader.
Deadpool Appeared in X-Men Origins: Wolverine... which was absolutely shit and ruined Deadpool. But there is a script for a more awesome Deadpool film which follows the comics more closely but it hasn't been confirmed whether the film will be made as Fox are hesitant to make a superhero film for an adult audience as the script is like rated 15 or 18 or something. But the film will apparently feature Deadpool's trademark humor, will have nothing to do with the god awful Wolverine film and will have Deadpool break the fourth wall and address the viewer. But Deadpool will be appearing in his own game which is going to be legen -wait for it- Dary!