Christopher Robert Cargill is an American screenwriter, novelist, podcast host, and former film critic known under the pseudonyms Massawyrm and Carlyle. Cargill currently resides in Austin, Texas with his wife. He is best known for writing the films Sinister (2012), Sinister 2 (2015), Doctor Strange (2016), and The Black Phone (2021). He is a frequent writing collaborator of Scott Derrickson.

Sinister is a 2012 supernatural horror film directed by Scott Derrickson and written by C. Robert Cargill and Derrickson. It shows Ethan Hawke as a struggling true-crime writer whose discovery of snuff films depicting gruesome murders in his new house puts his family in danger. Juliet Rylance, Fred Thompson, James Ransone, Clare Foley, and Michael Hall D'Addario appear in supporting roles.