HBO Max has an It prequel series in the works that will tell Pennywise's origin story

Variety

Titled Welcome to Derry, the potential series will begin in the 1960s and depict the events leading up to It: Part One, the 2017 film based on the Stephen King horror novel. The story is also said to include the origin story of Pennywise the Clown. It: Part One and It: Part Two director Andy Muschietti will executive produce the series along with Barbara Muschietti and Jason Fuchs, who developed the story for the show with Fuchs writing the script.