Pennywise the Dancing Clown is a villain from the novel "It," written in 1986 by Stephen King, and a figure in a film based on the novel. The character is able to change its appearance at will, but it often looks like a clown. It feeds on scared children.
The novel's main protagonists call the creature "It." The creature comes from a void outside of the universe, perceives humans as a helpless source of food, and the form thought to be the closest to its true appearance is that of a giant female spider. It dwells in the sewers of a town called Derry, where it terrorizes and eats local children. The protagonists, a group of friends, fight and eventually kill the monster.