This is the OG monster of Stranger Things, stalking the town of Hawkins throughout season one. It vaguely resembles some sort of monstrous amphibian species and originates from the Upside Down before emerging through the gate to kidnap victims (such as Will and Barb). Season one's Demogorgon is an "adult," walking upright and even possessing some supernatural abilities such as low-grade telepathic or telekinetic abilities.