Long before Marvel or DC popularized the idea of a shared cinematic universe, the “King of Horror” Stephen King had already built a massive interconnected literary multiverse — and It is one of its central pillars.

This year, horror fans are once again reunited with Pennywise/It — one of the most terrifying clowns in American pop culture — through Andrés Muschietti’s film adaptation. As the primary antagonist of King’s novel It, the 1990 miniseries, and the new film adaptation, the monstrous clown has terrorized generations of audiences around the world.

Yet, unless they are long-time Stephen King loyalists, many viewers may not realize that the story of It — and Pennywise’s origin — is deeply connected to numerous other works in King’s vast body of writing. With his boundless imagination, Stephen King has long constructed an intricate “literary universe” weaving his novels together.

The Dark Tower Series

In both film adaptations, Pennywise is only described as an evil entity from another dimension — shapeshifting, immortal, and immensely powerful — though his origin remains mysterious to most viewers.

In the original novel, however, King scattered multiple clues hinting at It’s true nature, and all roads lead to his eight-book epic The Dark Tower.
At the center of The Dark Tower is a mythical Tower located in a parallel world called All-World. This Tower maintains the balance of the entire multiverse, including the human world. Meanwhile, It exists in a different plane known as the Macroverse, where the creature slumbers for 27 years at a time before awakening to feed.

One of the twelve “Guardians” protecting the Tower is Maturin the Turtle — It’s eternal nemesis. Their conflict stretches back to “the beginning of all time,” embodying the cosmic struggle between Light and Darkness across the multiverse. Maturin is directly referenced in dialogue among the kids in the 2017 adaptation.

Furthermore, the mysterious power fueling It is known as the Deadlights, the very same cosmic force utilized by two major Dark Tower villains: The Crimson King and Walter Padick. One of the Crimson King’s demon servants, Dandelo, shares a nearly identical nature to Pennywise — leading fans to believe the two may be the same species or even the same entity manifesting differently.

Dreamcatcher

Derry — the town where It awakens every 27 years — is also the setting for several other peculiar Stephen King stories. Among them is Dreamcatcher, the tale of four childhood friends gifted with supernatural abilities as they attempt to stop an alien invasion.
Although the 2003 film adaptation omits the town’s name, the novel confirms that the story takes place in Maine — and remains tied to King’s larger universe through Derry.

Christine

In both the novel Christine and its 1983 film adaptation, a 1958 Plymouth Fury becomes possessed and kills nearly everyone it encounters. Interestingly, in It, Pennywise briefly uses a car of the same model to pick up Henry Bowers after he escapes from a mental institution.
If the two vehicles are indeed the same, then the demonic force behind the murders in Christine might be none other than Pennywise itself.

Misery

Bestselling novelist Paul Sheldon — author of Misery’s Child — is kidnapped by his deranged superfan Annie Wilkes and imprisoned in her remote mountain home. The story seems completely standalone… until Sheldon reveals that he once lived in Derry as a child.
Not only that, but his mother was close friends with the mother of Eddie — one of the seven members of the Losers’ Club in It.

The Shining

Fans of King’s classic novel The Shining or Stanley Kubrick’s iconic 1980 film adaptation will remember Dick Hallorann — the compassionate cook at the haunted Overlook Hotel, gifted with psychic abilities.

In It, Hallorann receives a brief mention. He once worked with the father of Mike Hanlon — before the tragic fire that claimed Mike’s parents.

Carrie

One of the most disturbing scenes in the 2017 It adaptation is Beverly leaning over the bathroom sink drain before a massive fountain of blood erupts, drenching the room and covering her from head to toe.

This moment is far more graphic than in the miniseries or the novel. For die-hard fans, the imagery immediately echoes Carrie, another one of King’s most beloved works.
In Carrie, the telekinetic protagonist is drenched in pig’s blood during a cruel prank — triggering her psychic rampage that kills nearly everyone at prom.

While the 1976 film adaptation remains a classic, the 2013 remake starring Chloë Grace Moretz received mixed-to-negative reviews.

11/22/63

Even after It concludes, two members of the Losers’ Club — Richie and Beverly — make cameo appearances in King’s 2011 novel 11/22/63.
While traveling through time, protagonist Jake Epping encounters the pair. Through this meeting, he grows aware of the multiverse, where angels, demons, extraterrestrials, and cosmic beings like It coexist. The novel was adapted into a television mini-series starring James Franco.