Pennywise's origin story in IT and It: Welcome to Derry shows the complex mythology behind the terrifying monster. The residents of Derry, Maine are visited by Pennywise every 27 years, and It: Welcome to Derry season 1 follows one of these brutal killing sprees in the early '60s. The two-part IT movie further cemented Pennywise as an iconic horror movie villain, while It: Welcome To Derry exposed more of his dark beginnings. The origins of Pennywise in Stephen King's IT novel were both quite ambiguous and, in many ways, incredibly complex, and It: Welcome to Derry honored King's story by portraying the complex, changing form of Pennywise. However, It: Welcome to Derry not only reinstated many novel details, but the show even expanded on them.