The Secret Agent: A Simple Tale is a novel by Joseph Conrad, first published in 1907. The story is set in London in 1886 and deals with Mr. Adolf Verloc and his work as a spy for an unnamed country (presumably Russia). The Secret Agent is one of Conrad's later political novels in which he moved away from his former tales of seafaring.

The novel is dedicated to H. G. Wells and deals broadly with anarchism, espionage, and terrorism. It also deals with exploitation of the vulnerable in Verloc's relationship with his brother-in-law Stevie, who has an intellectual disability. Conrad’s gloomy portrait of London depicted in the novel was influenced by Charles Dickens’ Bleak House.