Knull, also known as the King in Black and the God of the Symbiotes, is one of the most terrifying and ancient villains in the Marvel Universe. Created by writer Donny Cates and artist Ryan Stegman, Knull made his first full appearance in "Venom" (Vol. 4) #3 in 2018. His story delves into cosmic horror and ancient mythology, providing a dark origin for the symbiotes, including Venom.

### Origin and Background
Knull is an ancient entity, predating the universe itself. Born in the primordial void that existed before the creation of the universe, Knull existed in darkness and solitude. He thrived in this nothingness and was enraged when the Celestials, cosmic beings of immense power, began creating the universe, filling the void with light and life.

### Transformation into the King in Black
Fueled by his anger towards the Celestials for disrupting his dark realm, Knull retaliated by creating the first symbiote, a weapon known as the All-Black, the Necrosword. With this sword, Knull decapitated a Celestial, marking the beginning of his crusade against the light. The head of this Celestial would later become Knowhere, a space station and notable location in the Marvel Universe.

Knull’s use of the Necrosword made him immensely powerful, and he continued to wage war against the Celestials and other cosmic entities. However, he was eventually overpowered and cast back into the void. In his exile, Knull turned his attention to creating the symbiote race, using his divine power to craft living weapons from the darkness.

### The Birth of the Symbiotes
Knull’s symbiotes, known as the Klyntar, were initially an extension of his will. They spread across the universe, bonding with hosts to form powerful warriors. However, over time, the symbiotes began to develop individual consciousnesses and emotions, rebelling against Knull’s control. They trapped him on the planet Klyntar, which means "cage" in their language, and sought to atone for the evil they had done under his influence.

### The King in Black Rises
Knull’s imprisonment did not last forever. As he remained dormant, he awaited the day he could reclaim control over the symbiotes and resume his war against the light. His influence was felt through various hosts, most notably Eddie Brock, the human host of Venom. Knull's awakening was foreshadowed through numerous events in the Marvel Universe, leading to the "King in Black" storyline.

### The King in Black Event
In "King in Black," Knull finally breaks free and launches a full-scale invasion of Earth, seeking to envelop the planet in darkness and reclaim his throne as the supreme god of the symbiotes. His arrival brings untold destruction, as he uses his powers to control the symbiotes and spread chaos.