C. Robert Cargill is an American screenwriter, novelist, podcast host, and former film critic. He is known for his work under the pseudonyms Massawyrm on Ain't It Cool News and Carlyle on Spill.com. Cargill currently resides in Austin, Texas, with his wife.

He has made significant contributions to the film industry, notably as a writer for the films Sinister (2012), Sinister 2 (2015), Doctor Strange (2016), and The Black Phone (2021).

Cargill is a frequent collaborator with director Scott Derrickson and has a rich history in film criticism, having written for over ten years at Ain't It Cool News and contributing to Film.com and Hollywood.com.