Gunn and his brothers all attended the Jesuit St. At the age of 12, he began making 8 mm zombie films with his brothers in the woods near their home. He read magazines like Fangoria and attended genre movie screenings, including the original Dawn of the Dead at the Tivoli Theatre in St.
Growing up, Gunn was influenced by low-budget films such as Night of the Living Dead and Friday the 13th. Gunn has stated that his family's surname was originally the Irish name MacGilgunn and that it means 'sons to the servants of the god of the dead' it actually means 'son of the brown one.' Gunn was raised Catholic. His father was from an Irish immigrant family. He has five siblings - actor Sean, actor and political writer Matt, screenwriter Brian, Patrick, and Beth. Louis, Missouri, to parents Leota 'Lee' (Hynek) and James F.
