Lovecraftian horror is a subgenre of horror fiction that emphasizes the cosmic horror of the unknown (or unknowable) more than gore or other elements of shock. It is named after American author H. P. Lovecraft (1890–1937). His work emphasizes a philosophy of cosmicism, the idea that the reality underlying the veneer of normality is so alien that seeing it would be harmful.

Some scholars use "Lovecraftian horror" and "cosmic horror" interchangeably. Cosmic horror has been characterized as:

1. The "fear and awe we feel when confronted by phenomena beyond our comprehension, whose scope extends beyond the narrow field of human affairs and boasts of cosmic significance".

2. A "contemplation of mankind's place in the vast, comfortless universe revealed by modern science" in which the horror springs from "the discovery of appalling truth".

3. A naturalistic fusion of horror and science fiction in which presumptions about the nature of reality are "eroded".