Deadpool's background is vague and ambiguous, though it's unsure if this is intentional.
Due to his mental condition, the character cannot remember his history, so this plays out as we try to put together his history.
Expectantly, there are a few background stories in the comic book runs.
The character T-Ray claims in Deadpool #33 that he is the real Wade Wilson and that Deadpool is a vicious murderer who stole his identity.
Three issues later in Deadpool #36, the villain Loki claims to be Deadpool's father. Even Deadpool himself jokes to the reader that he is only named Wade Wilson at the whim of whatever writer or reader desires.
He seems to vaguely remember an upbringing in Ohio, but Deadpool is unsure of the validity of it.
Before the Weapon X scenario, he found himself working for the Yakuza in Japan, but he returned to America after falling in love with a boss' daughter.
A random couple found the mercenary in the woods wounded, and they take him in. As the mercenary heals, he becomes intrigued by the man's wife.
Envious, he burns the house down and kills the husband. In the process, he accidentally kills the wife.
He takes the name Wade Wilson in this story, assuming the wife's husband's name, but continues his life as a merc.
In the 2011-2012 series, a flashback reveals partially that Deadpool is the son of a decorated war hero, and is from Canada.
However, this conflicts with the original back story that he was kicked out of the U.S. Army Special Forces after being a part of the aforementioned program, Weapon X.
As a mercenary—that is, one who fights for his or her own interest and not that of a country or ideology—Deadpool is a rogue loner, and is a skilled assassin.
He is skilled in multiple traditions of the martial arts, and has a United States Army background. Within a magic satchel, he carries around what seems to be countless weapons and ammunition.
Deadpool is multilingual and speaks English, German, Japanese and Spanish.
He conceals or alters his presence by using a holographic disguise, and also deals with his opponents by supposedly being able to read the issues of other characters' comic books.
He can also teleport.
In 2008, Deadpool made the “Top 200 Comic Book Characters of All Time” list by Wizard Magazine, placing 182nd.
Empire Magazine places Deadpool at 45th place in “The 50 Greatest Comic Book Characters” list, and he ranks 31st on IGN's “Top 100 Comic Book Heroes.”