Marginalia is a collection of Fantasy, Horror and Science fiction short stories, essays, biography and poetry by and about the American author H. P. Lovecraft.

The dust-jacket art is a reproduction of Virgil Finlay's illustration for Lovecraft's story "The Shunned House."

Marginalia contains the following: New York Times reviewer Marjorie Farber said Marginalia "should cause intense satisfaction among the disciples of the late great Master of Necrology", commenting that Lovecraft's "whole career seems an effective protest against 'natural laws', against genuine scholarship and against literary craftsmanship".

[1] E. F. Bleiler noted that "The guest memoirs and essays are of varying interest", but that "Lovecraft's fiction is juvenile or minor.

[2] Lovecraft bibliographer Francis T. Laney described the volume as "a glorified fan magazine in book format.