This study concerns a Gothic realism in the dark, sensorial epistemologies emerging from intersections of documentary and horror cinema. From the ineffable subjects of horror documentaries and pseudo-documentaries, to the obsessive chroniclers of mockumentary horror cinema, the films examined here express generalized millennial and 21st-century archival anxiety around an unsettled and unsettling hypermediated reality. Part I focuses on gothumentaries, nonfiction works evoking the Gothic's unreadable subjects and undetected realities. Case studies show key documentary films such as Capturing the Friedmans, Cropsey, and The Hellstrom Chronicle bringing Gothic-horror tropes and conventions to bear upon documentary subject matter to produce skepticism of American environmental, social, and national stability from the 1970s onward. Part II explores mockumentary, fake found-footage, and screenlife horror cinema that turns to strategies of documentary and factual discourse to express an archival anxiety around human interaction with recording technologies. Case studies of pivotal films such as The Blair Witch Project, Diary of the Dead, Lake Mungo, Unfriended, Sickhouse, and We Are All Going to the World's Fair turn to Gothic reflexivity as a way of expressing the subject's relationship to, and experience of, a modernity that overwhelms in terms of its immensity, speed, and recordability.