The greatest healing factor in the Marvel Universe does not belong to Wolverine or Deadpool, but to the little-known Mister Immortal. Initially created by the legendary John Byrne as something of a joke, subsequent creators have fleshed out Mister Immortal’s backstory, giving it a dark twist and revealing his healing factor is tied to the fabric of reality itself.
In 1989, Byrne took over writing and drawing West Coast Avengers with issue #46. He inaugurated his run by introducing a new team of Avengers, called the Great Lakes Avengers. The team, led by Mister Immortal, consisted of the size-altering Bertha, the reptilian Dinah Soar, Doorman, and Flatman. The team was largely played for laughs. Their initial appearance brought them to Hawkeye’s attention, who traveled to meet the unsanctioned Avengers team. Readers got to see the group in action, but it was clear they needed guidance, and Hawkeye was just the man for the job. After the first storyline, the team would make sporadic appearances, and even recruited Squirrel Girl at one point. The Great Lakes Avengers are almost always portrayed as a joke, but over the years readers have learned the team’s leader has one of the most unique backstories in the Marvel Universe; readers also learn destiny has larger plans for him.
Mister Immortal’s real name is Craig Hollis, and he is mutant… sort of. Mister Immortal is a member of Homo Supreme, the final evolutionary stage beyond Homo Sapiens and even beyond Homo Superior. His regenerative ability was activated when he attempted suicide and after realizing his new powers, he would embark on a heroic career as Mister Immortal, ultimately forming the Great Lakes Avengers. Over time, however, other creators added a supernatural layer to Mister Immortal; it was revealed he lived under the patronage of the Deathurge, who would goad Mister Immortal into dangerous stunts, while always protecting him. Deathurge also revealed that Mister Immortal will see the end of the universe and in Immortal Hulk #24, readers indeed see Mister Immortal at the end of time, but ironically, he was dead. Metatron, the embodiment of the Eighth Cosmos, informed the Hulk that Franklin Richards was intended to be the last being left alive in the universe, setting him up to become the next Galactus and Mister Immortal was intended to be a backup in case anything happened to Franklin.
Both Wolverine and Deadpool’s healing factors are tied to their biology—Wolverine because of his mutation and Deadpool due to genetic enhancements. Mister Immortal’s healing abilities are multi-faceted: on one level they do indeed derive from a mutation, but there is also a cosmic aspect to them as well. As mentioned earlier, Franklin Richards is slated to become the next form of Galactus in the next cycle of creation—this is a crucial role in the Marvel Universe, as it keeps creation balanced. Mister Immortal is the backup—itself an important role. Thus, the universe needs Mister Immortal alive, and it will do what it takes to accomplish that, be it the patronage of the Deathurge or making him Homo Supreme.
Deadpool and Wolverine’s healing factors are integral to who they are, but the best healing factor in the Marvel Universe goes to Mister Immortal, who seems to have the protection of the universe itself.