Wikipedia
Gwendolyn "Gwen" Poole is a fictional character who appears in American comic books published by Marvel Comics, originating as an amalgam of Gwen Stacy and Deadpool from a variant cover of "Deadpool's Secret Secret Wars #2"., one of twenty variant covers published due to the popularity of Spider-Gwen from June 2015.
As a result of the character becoming popular with fans, used as a basis for cosplay, Marvel produced two stories featuring Gwenpool as a character, a backup story in the series " Howard the Duck", and a one-shot "Gwenpool Special #1". A retcon in the Howard the Duck #2 backup revealed her name to actually be "Gwen Poole", not Gwen Stacy, or even an alternate version of Gwen Stacy. Following the publication of the one-shot, an ongoing series titled The Unbelievable Gwenpool by the same creative team was announced, which started in April 2016.