What is the name of the clown in Stephen King's "IT"?

The answer is: Pennywise

Pennywise the Dancing Clown became a cultural phenomenon through Tim Curry's unforgettable portrayal in the 1990 miniseries, but the character in King's novel is far more bizarre. The dancing clown is actually just one form of an ancient cosmic entity that crash landed in what would become Derry, Maine millions of years ago.

This creature, which the kids nickname "IT," awakens every 27 years to feed on children, using their fears to season its meat. It takes the form of Pennywise because children are easier to lure when it appears as something cheerful and entertaining. The novel reveals that Its true form exists in a realm called the Deadlights, which can drive humans insane just by looking at them.

The character returned to terrorize audiences in 2017 through Bill Skarsgård's performance, which played up Pennywise's more predatory nature. His unsettling grin and wandering eye were actually happy accidents from Skarsgård's ability to move his eyes independently, creating a subtle but deeply unsettling effect that added another layer to the character's otherworldly nature.