How did Deadpool become the king of breaking the fourth wall?

The answer

Deadpool first appeared in New Mutants #98 in 1990, created by Rob Liefeld and Fabian Nicieza, as a serious mercenary villain with no fourth-wall awareness. It was not until writer Joe Kelly's acclaimed 1997 Deadpool series that Wade Wilson began acknowledging his fictional nature. In issue #28, Deadpool referenced a previous 'issue sixteen' as if reading his own comics. The full breakthrough came in issue #33, when he declared, 'None of this is actually happening. There is a man. At a typewriter.' Ironically, She-Hulk had been breaking the fourth wall in Marvel Comics since the 1980s, but Deadpool became its most famous practitioner, defining the character across all media.