That's why Pennywise always loses! Maturin in Stephen King's mythology.

Who is Maturin in Stephen King's works and what real role does he play in the development of the plot, and not just in decorative lore? Why was he cut out of the "IT" movies?

Fan art by Maturina, Slumbering Beast by A.L Stanford

What can be stated with high confidence:

Fact 1. Maturin is a cosmic being introduced in the novel "It" (1986) and deployed in the "Dark Tower". He is depicted as an ancient Turtle that exists outside of ordinary time and space. Fact 2. Maturin is an antagonistic counterbalancing being in relation to Ono (Pennywise). In King's canon, he's not Ono's enemy, but he's not Ono's ally either—that's fundamentally important.

Fact 3. Maturin is connected with the concept of Creation through thought/word. In "It" it is said that he "tore the universe out of himself" (a metaphor for the birth of the cosmos), and this is consistent with King's recurring motif of creation through consciousness. Fact 4. Maturin helps the "Losers Club" through a ritual, but does not interfere directly. He gives knowledge and direction, but does not solve the problem for the characters.

Fan art by Maturina

What is NOT a fact, but is often erroneously stated:

Myths: Is Maturin a "good god"? No. It is a neutral cosmic being. He is closer to the deistic principle: he created and departed. His "kindness" is a human interpretation. Is Maturin the direct creator of It? There is no direct textual evidence for this. They exist in the same cosmic order, but their origins are different. Is Maturin actively involved in the events? On the contrary, his key trait is passivity and detachment.

His real influence on the plot 

 It is the limiter of omnipotence. Without Maturin, It would look like an absolutely invincible evil. The turtle introduces a balance: It is not the only ancient creature in the universe. This is critically important: otherwise, the conflict would lose tension and turn into a hopeless horror without meaning.

The victory of the Losers Club does not look completely arbitrary, because: "IT" is limited in its abilities (the Derry barrier), Maturin provided information on how to defeat the clown, but in the end it all depends on how the characters behave.

The barrier around Derry, by the way, is in the shape of a turtle.

Maturin symbolizes: a creator god without personal intervention (deism), an old, tired wisdom opposed to chaotic, parasitic evil, It is the limit of human knowledge. From a religious point of view, Maturin is not a god, but a created, albeit cosmic, being, which fundamentally distinguishes him from the Christian understanding of the Creator. King deliberately avoids the absolute god in the text.

Why isn't he in the movie and TV series? The film adaptations of "It" are fundamentally autonomous. They don't need a shared space—just a local Derry plot. Maturin doesn't move the plot forward, he substantiates it. Simply put: without Maturin, the film is worse in meaning, but with Maturin, it risks being worse as a film.

Interesting fact: In the book, when "It" encounters the grown-up "Losers," it says that the turtle, Maturin, is dead and has been strangled. Later, during another ritual, Bill realizes that "It" wasn't lying.

P.S.: The connection of "It" with the "Dark Tower"

Maturin is one of the "Beams" supporting the Tower. Through him, "It" ceases to be the local history of the town of Derry and becomes part of King's overall meta-plot.

That's what kind of turtle is in the series.

The Dark Tower is the central axis of Stephen King's universe, a series of 8 novels and at the same time a metaphysical structure that keeps all worlds from disintegrating. Quite simply, the Dark Tower is the "supporting pillar" of reality. You can't see her, you hardly know about her, but without her, the world wouldn't exist.