The monsters of Stranger Things are more than just horror set pieces. Each one is connected to the show's larger mythology — the Upside Down, Hawkins Lab, and the entity that ties them all together. This guide covers every major creature in the series, from the Demogorgon to Vecna, with their origins, abilities, and the weaknesses the party uses against them.
The Demogorgon is the first monster audiences meet, and the one that defined the show's horror tone. It appears in Season 1 as a humanoid predator with a flower-like head that opens into a ring of teeth. It is fast, strong, and drawn to blood — which is why it targets Will in the opening episode and later Barb.
Origin: The Demogorgon is a creature native to the Upside Down, able to cross into Hawkins through the gate opened by Eleven at Hawkins Lab.
Weaknesses: Fire, coordinated group attacks, and being pulled back through the gate. Eleven is able to banish it at the end of Season 1.
The Demodogs, or "Demo-dogs," appear in Season 2 as a smaller, faster stage of the Demogorgon lifecycle. They are pack animals, and they are controlled by the Mind Flayer. Dustin's "pet" Dart is revealed to be a Demodog in one of Season 2's most heartbreaking subplots.
Origin: The Demodogs are the larval and adolescent stages of the creatures that inhabit the Upside Down's tunnels beneath Hawkins.
Weaknesses: Fire, the closing of the gate, and — occasionally — emotional bonds with specific humans.
The Mind Flayer is the main antagonist of Seasons 2 and 3. It is a massive, shadowy entity that exists in the Upside Down and possesses a hive-mind control over all other creatures. It possesses Will in Season 2 and Billy in Season 3, and it ultimately wants to merge the Upside Down with the real world.
Origin: First encountered by Will as a shadow in the Upside Down sky, the Mind Flayer is a fragment of a larger entity that we learn in Season 4 is tied to Vecna himself.
Weaknesses: Closing the gate, cutting off its hosts, and — temporarily — the combined firepower of the party.
Vecna is the true villain of Stranger Things. Revealed in Season 4 to be Henry Creel — a psychic child raised in Hawkins Lab — he is the entity behind the Mind Flayer, the Demogorgons, and the opening of the gates. He kills his victims by invading their minds and breaking their bodies.
Origin: Henry Creel was born with psychic abilities. He killed his family, was taken in by Dr. Brenner, and was ultimately defeated by Eleven and cast into the Upside Down, where he became Vecna.
Weaknesses: Music (specifically, the favorite song of his target can pull them out of his trance), and being physically attacked in the real world.
The Demobats are the winged creatures that inhabit the Upside Down in Season 4. They serve Vecna and are responsible for the death of Eddie Munson in the season finale. They are small individually but devastating in swarms.
Origin: Like all Upside Down creatures, the Demobats are part of the hive mind controlled by Vecna.
Weaknesses: Loud noise, coordinated distraction, and fire.
At the end of Season 3, the Mind Flayer takes on a massive physical form made from the melted bodies of Hawkins residents, resembling a giant spider. This is the creature that attacks the Starcourt Mall in the season finale.
Every fan has a favorite monster. But what if you are the monster? Our villain quiz matches you with one of six Stranger Things antagonists based on how you handle conflict, control, and consequences.