Stranger Things Season 4 introduces Vecna, revealed by the Duffer brothers to be Henry Creel, the original test subject 001 at Hawkins Lab, transformed by the Upside Down. As a sentient, traumatizing antagonist, Vecna serves as the "architect" of the dimension's creatures, including the Mind Flayer. Read a detailed breakdown of the character on Stranger Things Wiki .

2022---Stranger-Things--the-Duffer-brothers-reveal-who-is-Vecna--the-new-enemy-of-season-4