The King in Black is an elder god and father of the symbiotes (or Klyntar) within the Marvel Universe who made his first appearance in a Venom comic–but little do many fans know, the X-Men already had their own version of the ‘King in Black’ long before Knull ever hit the scene.
Knull aka the King in Black made his debut in Venom #3 by Donny Cates and Ryan Stegman, and his full backstory was described in the following issue. As revealed in Venom, Knull existed before there was light in the universe, and he alone held dominion over the perpetual void. When the universe was created and light and life started pouring into his kingdom, Knull responded by shaping the void into a sentient race of lifeforms: the Klyntar. Knull’s first use for his symbiotes was the forging of his All-Black Necrosword, which he used to cut the head off a Celestial as well as murder many other Marvel gods. Eventually, the King in Black had created enough Klyntar to form an army, one which he dispatched across the cosmos to unite the minds and bodies of everyone they possessed into his endless void.
In Amazing X-Men #2 by Fabian Nicieza and Andy Kubert, the X-Men are continuing their mission to free humans and mutants from Apocalypse's prisons (known as pins) throughout the villain’s domain. This series takes place in the Age of Apocalypse timeline, meaning Apocalypse has essentially conquered the world and has imprisoned anyone who opposed him with the help of his loyal followers. One of the most effective of Apocalypse’s Horsemen is a villain known as Abyss–a mutant with a particularly insidious power that makes him akin to the King in Black himself.
Age of Apocalypse’s Abyss is the X-Men’s Version of the King in Black
Like the King in Black, who is the literal god of the abyss, Abyss is a being of darkness who is able to become and move through shadow. Abyss can stretch, separate, and contort his body the same way a symbiote can, despite not being connected to the Klyntar in any known capacity. Where Abyss and Knull are the most similar, however, isn’t in their physical appearance or abilities, but their respective connection to the void. Abyss has access to the void, and its entry-point is literally located in his chest cavity. Throughout this issue, readers witness Abyss slinking through the shadows of this ruined world, encompassing people (in one instance, a child), and dropping them into the void through the portal in his chest.
The King in Black is the god of the abyss and the ruler of the void as depicted in the Venom series, and for all intents and purposes, so is Abyss. This Horseman of Apocalypse has shown a mastery of the void that even rivals that of Knull–plus, Abyss was around first as he made his Marvel Comics debut in the ‘90s while Knull wasn’t introduced until 2018. So, from his powers and abilities to the fact that he was literally introduced first, it seems clear that X-Men had its own ‘King in Black’ long before Venom.