The Jackson is a monstrous religious fanatic and vigilante from one of several alternate futures.
The son of Zachary Johnson and Tamra Dixon, he lost his father at an early age and in order to avoid The Wasting, he was taken into the distant future by the Brothers of Trouble, a religious group that worshiped the hero Jack-in-the-Box as a god. With no contemporary version of the Jack in their time, the Brothers decided to make one by altering the boy, making him stronger and faster than a normal human and endowing him with sharp claws and teeth.
Christened "The Jackson", he waged a violent war on crime, and eventually was sent back in time to prevent his alternate-reality counterpart, The Box, from killing "The Jack". When Jack-In-The-Box prevented him from killing The Box, Jackson became convinced that Jack must be an impostor, and thus formed a temporary truce with The Box to kill him. Jack led the two pretenders to an old junkyard, where he managed to freeze Jackson with a compressed coolant blast, while immobilizing The Box with an electromagnet.
The two miscreants were incarcerated, but managed to escape back to their own respective timelines. Shaken by the experience, and by his encounter with Jerome Johnson, another potential version of his son, Johnson elected to quit being a superhero, hoping to prevent either of the futures represented by The Box and Jackson. Though Jackson vowed to return, it remains unrevealed whether or not his future still exists.