Perhaps the most popular existential work of the 20th century was written by a man who has not usually been identified as a philosopher, but whose work clearly embodies existential themes. Dashiell Hammett, creator of the hard-boiled detective novel, applied an existential viewpoint to his writing. His novel The Maltese Falcon is an excellent example of literature in which existential themes run through the story.

The Maltese Falcon begins when a young and very attractive women, Brigid O'Shaughnessy, approaches private detective Sam Spade and his partner, Miles Archer. She wishes to hire them to rescue her sister from Floyd Thursby, whom she believes has her sibling under his control. Spade and his partner take the case, but it results in the murder of Archer. It also compels Spade into a hunt for a mysterious statue in the shape of a Falcon, which is allegedly encrusted with jewels. In the end, Spade solves the murder of Archer and turns the perpetrator over to the police even though it may ultimately not be in his best interest to do so. But as Spade says, "when a man's partner is killed, he has to do something about it."

Existentialism, as defined by Sartre, Camus, Kierkegaard and others, begins with the premise that 'existence precedes essence'. For many other philosophical systems, the essence of a person is present at birth. For existentialists, however, an individual must define his or her own reality.