Deadpool is unpredictable and brash at times and is ultimately a unique character who is hard to put a finger on. Some argue that the Merc with a Mouth is indeed a mutant given his origins, but there is a difference between him and a naturally born superhuman.
For example, humans like Captain America, the Hulk, and Spider-Man received their superpowers through an outside source to make them into what is called a "mutate." In contrast, to be classified as a Mutant means someone whose genetics are altered due to a natural mutation in the human genome - but in Wade Wilson's case - his powers came from being tested on - not an evolution. Seemingly, it was these external experiments that gave Deadpool his powers - but one could say that the testing just awakened the powers he already had.
One way to decipher whether Deadpool was a mutant or a mutate is by asking a very simple question: did his powers come naturally or did he get them from somewhere else? Wade, like Wolverine & Captain America: Weapon Plus #1, readers got a glimpse of a chalkboard that shows the generational line of test subjects in one of Weapon Plus' labs. It is at this moment that Rob Liefeld and Marvel confirmed Deadpool as Weapon IX. Meaning Deadpool's powers may not have been activated, but created.
That confirmation from Deadpool's creator doesn't stop readers to place Wade in the mutant category, which makes sense because of his close relationship with mutants as seen in the comics and in the movies. This makes Deadpool an even more interesting character because through these mediums he is still able to break the fourth wall - making him resonant with fans - but his origins are not as original as some may think. In fact, Deadpool was created in the image of another assassin named Deathstroke (aka Slade Wilson). Coincidence? Nope. Co-creator Fabian Nicieza and Rob Liefeld decided to pay homage to the DC character by giving their version of a serious assassin a similar name, costume, and abilities.
In Deadpool's first appearance in Marvel Comics New Mutants #98, he was written as a mercenary who came out of nowhere to attack the hero known as Cable. At the time, Deadpool's only known ability was super agility and his Weapon Plus ties hadn't been created yet. So, how does Marvel explain his healing factor? And if Weapon Plus experimented on his body wouldn't they need subjects who already have healing powers? Now, , Captain America and Hulk did not have healing powers prior to their experiments. This is important because the answer to Deadpool's healing factor can be found in Deadpool and Death Annual #1.
In this story, Wade meets Death when he finds himself stuck in the "Department K medical facility," where he would undergo the treatments that will eventually turn him into Deadpool. With those experiments and terminal cancer eating away, Wade is close to dying, and Death would try to finish the job. What the grim reaper didn't expect was a Wade with newfound healing powers. Unfortunately, Death wasn't finished with Deadpool yet. In Deadpool #60, Weapon Plus takes away Wade's healing power and kills him. The arc that follows, Funeral for a Freak, Deadpool finds himself at peace in Death's arms.
Sadly for Wade, it wasn't long until he returns to life by Thanos. The Mad Titan would do this by casting a curse on Deadpool that brings him back permanently (the dude is now immortal!). Still, this does not make him a mutant according to the simple question asked earlier. Nonetheless, that doesn't stop some fans from adopting Deadpool as a mutant.
