The Big Sleep (1939 (1939 in literature)) is a hardboiled crime novel by Raymond Chandler, the first in his acclaimed series about detective Philip Marlowe. The work has been adapted twice into film, once in 1946 (The Big Sleep (1946 film)) and again in 1978 (The Big Sleep (1978 film)).

The story is noted for its complexity and is heavily influenced by classic Greek tragedy, with many characters double-crossing each other and many secrets being exposed throughout the narrative. The title is a euphemism for death; it refers to a rumination in the book about "sleeping the big sleep", and is not descriptive of the plot.

In 2005, Time (Time (magazine)) magazine included the novel in its 100 Best Novels published after 1923.