When Wade Wilson was diagnosed with cancer he allowed the scientists of Weapon X to try to cure him by recreating Wolverine's healing ability. They succeeded, but ultimately left him horribly disfigured.
Weapon X placed him in a prison lab as a failure. Upon escaping, Deadpool became a highly skilled mercenary, battling Cable, X-Force and others.
Deadpool has superhuman healing factor (which allows him to regenarate damaged tissue or even completely severed limbs), immortality (an alternate reality version of him was alive and still in business as Deadpool 800 years in the future!), immunity to telepaths, and peak-human / low-superhuman physicality (strength, agility, reflexes and durability).< LESS