Low fantasy, or intrusion fantasy, is a subgenre of fantasy fiction in which magical events intrude on an otherwise-normal world.[1][2] The term thus contrasts with high fantasy stories, which take place in fictional worlds that have their own sets of rules and physical laws.
Intrusion fantasy places less emphasis on elements typically associated with fantasy and sets a narrative in realistic environments with elements of the fantastical. Sometimes, there are just enough fantastical elements to make ambiguous the boundary between what is real and what is purely psychological or supernatural. The word "low" refers to the prominence of traditional fantasy elements within the work and is not a remark on the work's overall quality.
An alternative definition, common in role-playing games, rests on the story and characters being more realistic and less mythic in scope. Thus, some works like Robert E. Howard's Conan the Barbarian series can be high fantasy according to the first definition but low fantasy according to the second.[3] With other works, such as the TV series Supernatural, the opposite is true.