
During the second season, a massive creature made of smoke emerges from the alternate dimension, known as the Upside Down, and the kids nickname it “the Mind Flayer.” This creature begins to control the actions of people in Hawkins, ultimately leading to the death of Max’s brother, Billy. However, the Mind Flayer becomes less of a threat when a new villain, Vecna – revealed to be Eleven’s former acquaintance, Henry Creel – appears. While the creators, the Duffer brothers, hint that Vecna might be the main antagonist of the entire series, they haven’t confirmed it, leaving the story open as it nears its conclusion.