The character's popularity has seen him feature in numerous other media. In the 2004 series Cable & Deadpool, he refers to his own scarred appearance as "Ryan Reynolds crossed with a Shar Pei". Reynolds himself would eventually portray the character in the 2009 film X-Men Origins: Wolverine and reprised the role in the 2016 film Deadpool.
Created by artist/writer Rob Liefeld and writer Fabian Nicieza, Deadpool made his first appearance in the pages of The New Mutants #98 cover dated February 1991. According to Nicieza, Liefeld came up with the character's visual design and name, and Nicieza himself came up with the character's speech mannerisms. Liefeld, a fan of the Teen Titans comics, showed his new character to then-writer Fabian Nicieza. Upon seeing the costume and noting his characteristics (killer with super agility), Nicieza contacted Liefeld, saying "this is Deathstroke from Teen Titans". Nicieza gave Deadpool the real name of "Wade Wilson" as an inside-joke to being "related" to "Slade Wilson", Deathstroke.
Other inspirations were Spider-Man and Wolverine. Liefeld states: "Wolverine and Spider-Man were the two properties I was competing with at all times. I didn't have those, I didn't have access to those. I had to make my own Spider-Man and Wolverine. That's what Cable and Deadpool were meant to be, my own Spider-Man and my own Wolverine." Both Deadpool and Cable were also meant to be tied into Wolverines history already from the start, as Liefeld describes: "Wolverine was my guy. If I could tie anything into Wolverine, I was winning." What Danny DeVito's character was to Arnold Schwarzenegger's character in Twins, Deadpool was intended to be to Wolverine. And because Liefeld's favorite comic title before X-Men was Avengers, who had weapons like Captain America's shield, Thor's hammer and Hawkeye's bow and arrow, he decided to weaponize his new characters as well.
In his first appearance, Deadpool is hired by Tolliver to attack Cable and the New Mutants. After subsequently appearing in X-Force as a recurring character, Deadpool began making guest appearances in a number of different Marvel Comics titles such as The Avengers, Daredevil, and Heroes for Hire. In 1993, the character received his own miniseries, titled The Circle Chase, written by Fabian Nicieza and pencilled by Joe Madureira. It was a relative success and Deadpool starred in a second, self-titled miniseries written in 1994 by Mark Waid, pencilled by Ian Churchill, and inked by Jason Temujin Minor and Bud LaRosa. Waid later commented, "Frankly, if I'd known Deadpool was such a creep when I agreed to write the mini-series, I wouldn't have done it. Someone who hasn't paid for their crimes presents a problem for me."
In 1997, Deadpool was given his own ongoing title, initially written by Joe Kelly, with then-newcomer Ed McGuinness as an artist. Deadpool became an action comedy parody of the cosmic drama, antihero-heavy comics of the time. The series firmly established his supporting cast, including his prisoner/den mother Blind Al and his best friend Weasel. The ongoing series gained cult popularity for its unorthodox main character and its balance of angst and pop culture slapstick and the character became less of a villain, though the element of his moral ambiguity remained. The writer Joe Kelly noted, "With Deadpool, we could do anything we wanted because everybody just expected the book to be cancelled every five seconds, so nobody was paying attention. And we could get away with it." Reportedly Kelly introduced the fourth wall breaking gimmick.
The series was taken over by Christopher Priest who noted that he found Kelly's issues to be "complex and a little hostile to new readers like me" and that by issue 37, he realized that "it was okay to make Deadpool look stupid." Kelly may have introduced Deadpool to breaking the fourth wall, but Priest "could be credited for establishing it as an essential part of the characters personality and worldview." Priest left the series after only one year at issue #45.