The Black Winter devoured the sixth iteration of the cosmos,^[1] leaving only a single survivor - Galan of Taa, who it chose as its Herald.^[2] Known vaguely to the Asgardians as the Fimbulwinter, its coming was prophesized to herald the beginning of Ragnarok.^[5]

Seeking to take Galactus back into its service, the Black Winter encroached into the Prime Marvel Universe and attacked him - taking on the form of Thor Odinson. Galactus managed to escape, albeit severely wounded, and subsequently crash-landed in Asgard; where some of its dark frost infected Yggdrasill, causing the World Tree to slowly rot and die.^[3] While Galactus marked Thor Odinson as his newest Herald and began consuming five special planets that would theoretically give him the power to oppose it, the Black Winter attacked an alternate universe and was confronted by its league of heroes. Upon looking in its eyes, the league saw the face of the one who was destined to kill them, and called out to their gods for help before being killed. The Black Winter then extinguished that universe, assuming the form of the cosmic hand that had originally created it.^[6]

Returning to the Prime Marvel Universe,^[5] the Black Winter easily subdued Galactus and Thor. Intrigued by Thor's many brushes with death, the Black Winter pitted him against manifestations of his greatest enemies and mockingly informed him of what was supposed to be his true end; noting that someone or something was worming their way through time to derail destiny. Thor used a God-Blast to escape, prompting the Black Winter to again assume the form of a dark version of the Herald of Thunder before assuring him it had no intention of destroying his universe, ominously adding that much darker threats than it were coming. When asked what it actually wanted, the Black Winter mockingly revealed that Galactus had been lying to Thor and was actually its Herald, and that it had come to reclaim him.^[2]

Furious at this revelation, Thor drained Galactus of all of his power, leaving him a desiccated husk. When the Black Winter tried to take him, Thor refused and used Galactus' dead body as a bomb to obliterate the Black Winter. A single snowflake survived, offering to show Thor a vision of his end - a world in which Thanos had stolen Mjolnir and imbued it with the Infinity Stones, commanding an army of zombified heroes - before Thor crushed it to dust.^[7] However, according to the Watcher, Thor's belief that he had destroyed the Black Winter was false.^[8]

The Black Winter is able to generate frost and snow made up of eldritch darkness that disintegrates whatever it comes into contact with.^[6] As with Galactus, it appears differently to each person that sees it, usually taking on the form of the person or being fated to bring about the onlooker's demise,^[3] though it is capable of changing form at-will.^[2] The Black Winter is also capable of creating realistic illusions in the form of other entities in someone's mind.^[2]

• The Black Winter shares many similarities with Hunger, both being formless entities which devour entire realities, and with Omnipotentis, another devourer of universes. There is also the Griever at the End of All Things who also served as destroyer of universes.
• The league of heroes that confronts the Black Winter in Thor (Vol. 6) #2 is a nod to DC Comics' Justice League and mentions the major attributes of its seven major members. In addition, the comic also references the city of Metropolis, and Darkseid as their destroyer. After the slaughter of the heroes, the Black Winter takes the form of the hand that is shown having created the DC Universe in first place, before destroying it.

• The Black Winter is described as a "plague" and is the latest of many retcons of Galactus' origin story.^[9] It appears to be inspired by the "Creeping Plague" from the very first iteration of Galactus' origin story, as told in Thor #169. In the original origin story, Taa was implied to exist in the current universe, but the galaxy it was in was suffering from a plague where its inhabitants were all dying from an incurable sickness. (The affected worlds were not destroyed; only their people were killed.) The last people of Taa, choosing to die in blazing glory than sickness, decided to fly their ship into a star. The ship flew around the star and the star's radiation killed everyone except Galan, empowering him instead. This heavily outdated account was how Galan became Galactus, before his origin story got significantly reworked into being a survivor of a previous universe.