The thriller is a broad genre of literature, film, and television. It includes numerous, often overlapping sub-genres.

Thrillers are characterized by fast pacing, frequent action, and resourceful heroes who must thwart the plans of more-powerful and better-equipped villains. Literary devices such as suspense, red herrings, and cliffhangers are used extensively.

Characteristics

Thrillers often take place wholly or partly in exotic settings such as foreign cities, deserts, polar regions, or high seas. The heroes in most thrillers are frequently "hard men" accustomed to danger: law enforcement officers, spies, soldiers, seamen, or pilots. However, they may also be ordinary citizens drawn into danger by accident. While such heroes have traditionally been men, women are becoming increasingly common.

Thrillers often overlap with mystery stories, but are distinguished by the structure of their plots. In a thriller, the hero must thwart the plans of an enemy, rather than uncover a crime that has already happened. Thrillers also occur on a much grander scale: the crimes that must be prevented are serial or mass murder, terrorism, assassination, or the overthrow of governments. Jeopardy and violent confrontations are standard plot elements. While a mystery climaxes when the mystery is solved; a thiller climaxes when the hero finally defeats the villain, saving his own life and often the lives of others. In thrillers influenced by film noir and tragedy, the compromised hero is often killed in the process.

In recent years, when thrillers have been increasingly influenced by horror or psychological-horror exposure in pop culture, an ominous or monstrous element has become common to heighten tension. The monster could be anything, even an inferior physical force made superior only by their intellect ( as in the Saw (film series) movies), could be a supernatural entity (Dracula, Christine books, The Amityville Horror, Ringu films), aliens (H. P. Lovecraft's Cthulhu mythos books), serial killers (Stepfather, The Texas Chainsaw Massacre films), or even microbes or chemical agents (Cabin Fever, Richard Matheson's The Last Man On Earth). Some authors have made their mark by incorporating all of these elements (Richard Laymon, F. Paul Wilson) throughout their bibliographies.

Similar distinctions separate the thriller from other overlapping genres: adventure, spy, legal, war, maritime fiction, and so on. Thrillers are defined not by their subject matter but by their approach to it. Many thrillers involve spies and espionage, but not all spy stories are thrillers. The spy novels of John LeCarre, for example, explicitly and intentionally reject the conventions of the thriller. Conversely, many thrillers cross over to genres that tradtionally have had few or no thriller elements. Alistair MacLean, Hammond Innes, and Brian Callison are best known for their thrillers, but are also accomplished writers of man-against-nature sea stories.

Thrillers may be defined by the primary mood that they exhibit: excitement. In short, if it thrills, it is a thriller.