‘Stranger Things’ Season 5 trailer may have confirmed a huge fan theory, and it’s bad news for one character

'Stranger Things' 5 will have its first four episodes on Wednesday, November 26
UPDATED OCT 31, 2025
(L-R) Millie Bobby Brown, Finn Wolfhard, and Noah Schnapp return for 'Stranger Things' Season 5 (Cover Image Source: Netflix | @strangerthings)
(L-R) Millie Bobby Brown, Finn Wolfhard, and Noah Schnapp return for 'Stranger Things' Season 5 (Cover Image Source: Netflix | @strangerthings)

The new 'Stranger Things' Season 5 trailer might have confirmed one of the biggest fans' theories. The final chapter of the sci-fi series is slated to be released in three parts, with the first one releasing on Wednesday, November 26. However, before the grand release of the show, the intrigue and anticipation are mounting high. So much so that the sharp-eyed fans just spotted a detail in the trailer, confirming Venca (Jamie Campbell Bower) isn't the only threat Eleven (Millie Bobby Brown) and her friends will face in the final chapter.

Natalia Dyer, Caleb McLaughlin, Finn Wolfhard, Charlie Heaton, Joe Keery, and Gaten Matarazzo in Stranger Things (Image Source: Netflix | Stranger Things)
A still from 'Stranger Things' (Image Source: Netflix | @strangerthings)

According to the Mirror, a detailed fan theory surfaced on Reddit soon after 'Stranger Things' Season 4 ended in 2022. The fans suggested that "Season Five's villain is the Thessalhydra and it's been set up since Season 1." Like many of the monsters in 'Stranger Things,' the Thessalhydra comes from Dungeons and Dragons and is described as a massive, multi-headed creature with a huge mouth. According to the theory, hints about the monster appeared throughout the series, including during the group's first trip into the Upside Down in season 4.

The post noted, "They wonder what the heck it was and if it caused an earthquake or something, but the subtitles even say that it is a creature roaring off-screen. But the three of them are very busy doing Very Important Vecna Things, so they disregard the other random terrifying creature and press on." By the end of season 3, Eleven and her gang had already defeated one massive creature from the Upside Down, the giant, spider-like Mind Flayer. The theory suggests another powerful creature still threatens Hawkins, either a smart entity secretly controlling events or a monstrous being serving under Vecna.

Talking about the 'Stranger Things' Season 5 trailer, it shows Vecna returning in full form, confronting Will Byers (Noah Schnapp), and declaring, 'You are going to help me… one… last… time." Set in the fall of 1987, over a year after Season 4, the final season finds Eleven in hiding and training for Vecna's comeback while evading government forces occupying Hawkins. Series creators Matt and Ross Duffer also discussed the trailer's major reveals in an exclusive Entertainment Weekly interview.

Ross explains that the key to understanding Vecna's chilling line to Will goes back to Season 2, Episode 6, 'The Spy,' which he calls "the most important episode," noting, "Will was really working, in a way, for the Mind Flayer." He adds that in Season 5, "We start to learn more about what happened and what the connection is to all of this and Vecna."

Matt points out Will's importance to the series’ conclusion, saying, "Because the story really began with Will and his disappearance, it felt, in order to go full circle, it needed to really end with him in so many ways." He adds, "In the last couple seasons, we hadn't really centered much of the show on Will. So there was so much to explore with him from a character perspective and plot perspective."

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