Deadpool: Merc With a Mouth (2009)

Written by Victor Gischler with art by Bong Dazo, this 2009 series sends Deadpool to the Savage Land to retrieve a bioweapon for A.I.M.: the still-conscious severed head of a zombie-universe Deadpool (Headpool). The 13-issue run follows their cross-dimensional quest to get Headpool back to his own universe.