Deadpool (Marvel)

"Wait! You may be wondering, "Why the red suit?" Well, that's so bad guys can't see me bleed."

- Deadpool explains his red outfit.

Wade Winston Wilson, also known as Deadpool, is a major character from Marvel Comics, serving as an anti-hero/anti-villain in the majority of his appearances. He is a mutant mercenary with insatiable bloodlust and the uncanny ability to break the fourth wall, usually aware of the medium he is in.

History
Though published by Marvel, there is no escaping the fact that for all of his banter, popularity and personality, Deadpool is at heart a merciless assassin and psychopath: he has killed many people who deserved it but has also been quite happy to do away with innocent people for the right price.

Deadpool has always inhabited a crazy world of his own and as such really doesn't fit well with our ideals of "good" and "evil" - he can be a hero one moment and a villain the next. With this insane mind, he often breaks the 4th wall in many works he appears in, and people don't understand what he means as he's doing so.

Hulk Vs Wolverine
Deadpool was part of the Weapon X crew and an antagonist in this animated special - he worked alongside famous Wolverine foes Sabretooth, Lady Deathstrike and Omega Red, but showed himself as a trickster and psychopath just as he has always done in the past and became a more neutral force as the story progressed.

First Timeline
Deadpool was a villain in the live-action movie X-Men Origins: Wolverine - though this was a very different Deadpool from the wise-cracking anti-hero of the comic books, in the movie he was also given more powers than he traditionally has in the comic books - he is also mute (having no mouth to speak off) - instead of having two swords he actually has two extendable blades that can come out of his arms, similar to Baraka and was a brutal fighter working for William Stryker.

In the end he was decapitated by Wolverine but it required a team-up with his traditional rival, Sabretooth, to stand a chance against this powerful incarnation of Deadpool.

Second Timeline
In the second film timeline, Deadpool is reimagined as his more traditional anti-villain self, seeking to protect his girlfriend and get revenge on villains like Ajax.

Ultimate Marvel
in the Ultimate Marvel universe, Deadpool is envisioned as an anti-mutant extremist and a cyborg, in this universe he is the leader of the Ultimate Marvel version of the Reavers - who hunt mutants for sport as part of a twisted reality TV show.

Trivia

 * Deadpool is confirmed to be a parody of DC Comics' supervillain Deathstroke, whom he share many similarities with (Deathstroke's name is Slade Wilson, he has a healing factor, and is also a skilled assassin and marksman).
 * Deadpool fought Deathstroke in an episode of DEATH BATTLE and won. He later faced off against Pinkie Pie from My Little Pony: Friendship is Magic, but due to the two's shared ability to see past the fourth wall, they instead became friends and went on to troll Wizard and Boomstick by not killing each other and wrecking the show.
 * Deadpool was scheduled to return in the second season of Wolverine and the X-Men before it was cancelled.