The HBO series "IT: Welcome to Derry" has introduced a twist that sheds light on the origin story of Pennywise. The show's creators have provided explanations for key plot points, including Pennywise's entrance and a significant event in episode 5. The series appears to be expanding on the character's backstory, with some outlets suggesting that a major revelation about Pennywise's identity may have been revealed, although the details of the character's ultimate defeat are not entirely clear.