Stephen King's
The turtle is a force of benevolence and is guided by compassion, whereas IT represents chaos, evil, and fear. They are diametrically opposed. Because they are both interdimensional entities with equal powers, the turtle could kill IT if it wanted to, therefore it's understandable that IT is terrified of it.
A Turtle of massive size with an ancient appearance, Maturin existed long before the creation of the mainstream universe in Stephen King's novels. By nature, Maturin was kind, wise, loving, gentle, compassionate, benevolent, and had a very grandfather-like demeanor when he spoke to humans.
You've also probably read all of King's horror novels, including The Dark Tower series, which reveals that Pennywise's archenemy is The Turtle.
That is, when Pennywise morphs into a werewolf, he is subject to the same weaknesses as a werewolf, including silver slugs. In both the original novel and made-for-television adaptation, Pennywise is weakened using silver bullets melted down from earrings.
In their final battle, the Losers' Club was able to kill Pennywise by reducing him to a child-like form as they overcame their fears.
The spider-clown shrinks as the Losers hurl taunts at It, until it's tiny and weak enough that they pluck out its heart and squash it into nothingness. In the end, they defeat Pennywise by, uh, making him feel really bad about himself. It author Stephen King.
Stephen King's IT introduced readers to a one-of-a-kind creature that can take any form, the most common one being Pennywise the Dancing Clown, and as menacing as it is, this creature has one big enemy it's truly scared of: Maturin, the turtle.
A god of destruction, not just of our world, but of multiple worlds and even multiple universes. It originated in a vast cosmic void between worlds that has been called, at times, the Macroverse, and in King's Dark Tower series, the Todash Darkness, in a space It refers to only as the Deadlights.
As well as having his right arm bitten off, Georgie is trying to crawl away but he was dragged into the sewers and devoured by Pennywise, with an unnamed older woman and her cat being the sole witnesses of the horrific scene, including before Georgie lost his arm.
According to It, when humans got scared, "all the chemicals of fear flooded the body and salted the meat". This is why he prefers to feast on children -- their fears are simple, pure, and powerful compared to the complex, pathological fears of adults. Basically, children are delicious.
It comes in many shapes and sizes. Most iconically, It takes the form of Pennywise the Clown, whose real name is actually Bob Gray (anticlimactic, honestly).
Georgie's Arm ('It')
After a creepy conversation with Pennywise, the killer clown chomps on Georgie's arm, leaving the boy to drag himself to safety as blood pours into the raindrops on the street before he's pulled into the drain by Pennywise, never to be seen again.
Yup! He's a demon and the general idea is if you are not scare, it will only be harder for Pennywise to kill you as he needs to bait you. He can kill you if he wants to anytime and doesn't care. Although, if you are not scared, he will either leave you be for a little while or just kill you in the instant .
Muschietti appears to be implying Pennywise was a human familiar who It corrupted and then enjoyed so much It incorporated his shape into its file cabinet of monsters.
In the novel, It's origins are nebulous. He took the form of a clown most frequently, Mr. Bob Gray or Pennywise, but his true form is an ancient eldritch entity from another universe who landed in the town that would become Derry by way of an asteroid and first awoke in 1715.
Pennywise's origins are briefly explored in both the book and It: Chapter Two, where it's revealed that he is a being that crash-landed on Earth from another dimension hundreds of years ago.
Kersh is Pennywise's daughter.
Superhuman Strength: It can tear the heads and limbs of human bodies with extreme ease, either with arms or mouth (as Pennywise or any humanoid form). Superhuman Speed: Bill notes that It can move at extreme speeds, claiming that it was way faster than an "express train".
The rest of the group realizes they can defeat it by shrinking it and therefore weakening it, which they achieve by standing up to it. They take out IT's heart and proceed to crush it, finally killing it. Eddie dies and his body is left behind.
Humiliated, Pennywise begins to shrink, transforming into an almost Benjamin Button–like, melted clown-baby.
The winner is Lucifer Morningstar and maybe quite easily. Lucifer as his name suggests is The Devil of the DC Universe, he is by far one of the most powerful beings to exist. He is the first and most beautiful and the most powerful of all the angels in existence.
The Losers Club is the main protagonistic faction of Stephen King's novel It. They are a group of seven children, with six boys (later men) and one girl (later a woman) and they have unhappy lives which unite them.