In the novel, It claims that its true name is Robert "Bob" Gray, but decided to be named “It”. Throughout the book, It is generally referred to as male, usually appearing as Pennywise.

In the opening scene, viewers are treated to Pennywise's (Bill Skarsgård) first kill, which is as devastating as it is terrifying. Little Georgie Denbrough (Jackson Robert Scott) is out innocently playing on a rainy day when the evil clown sinks his teeth into him.

The novel explains that IT landed on Earth during an asteroid impact and established itself under the land Derry would be later built on, and initially preyed on indigenous tribes. From that point of view, IT/Pennywise would be billions of years old, but his clown shape wouldn't be that old.

It is the titular shapeshifting antagonist of the miniseries whose primary form is a wisecracking clown named Pennywise, played by Tim Curry.