"In the Walls of Eryx" is a short story by H.P. Lovecraft, written in January 1936 and first published in Weird Tales magazine in October 1939. It is unusual among Lovecraft's work as a standard science fiction story involving space exploration in the near future.

The story, written in first-person narrative, depicts the life and death of a prospector on the planet Venus who, while working for a mining company, becomes trapped in an invisible maze.