Question: Who wrote the 1986 novel that the 2017 horror movie is based on that features the actor from Hemlock Grove? 
Sentence (from "Bill Skarsgård"): Bill Istvan Günther Skarsgård (born 9 August 1990) is a Swedish actor and model, known for his roles in "Simple Simon", "Hemlock Grove", "Atomic Blonde" and Pennywise the Dancing Clown in the 2017 film "It".
Relevant evidence: Yes