A Series of Unfortunate Events is a series of thirteen children's novels written by American author Daniel Handler under the pen name Lemony Snicket. The books follow the turbulent lives of orphaned siblings Violet, Klaus, and Sunny Baudelaire. After their parents' death in a fire, the children are placed in the custody of a murderous villain, Count Olaf, who attempts to steal their inheritance and later, causes numerous disasters with the help of his accomplices as the children attempt to flee. As the plot progresses, the Baudelaires gradually confront further mysteries surrounding their family and deep conspiracies involving a secret society.

Characterized by Victorian Gothic tones and absurdist textuality, the books are noted for their dark humour, sarcastic storytelling, and anachronistic elements, as well as frequent cultural and literary allusions. They have been classified as postmodern and metafictional writing, with the plot evolution throughout the later novels being cited as an exploration of the psychological process of the transition from the innocence of childhood to the moral complexity of maturity. As the series progresses, the Baudelaires must face the reality that their actions have become morally ambiguous, blurring the lines between which characters should be read as "good" or "evil".

Since the release of the first novel, The Bad Beginning, in September 1999, the books have gained significant popularity, critical acclaim, and commercial success worldwide, spawning a film, a video game, assorted merchandise, and a television series. The main thirteen books in the series have collectively sold more than 60 million copies and have been translated into 41 languages. Several companion books set in the same universe of the series have also been released, including Lemony Snicket: The Unauthorized Autobiography, The Beatrice Letters, and the noir prequel tetralogy All the Wrong Questions, which chronicles Snicket's childhood.