Atlas Shrugged is a 1957 novel by Ayn Rand. It is her longest novel, the fourth and final one published during her lifetime, and the one she considered her magnum opus in the realm of fiction writing. She described the theme of Atlas Shrugged as "the role of man's mind in existence" and it includes elements of science fiction, mystery, and romance. The book explores a number of philosophical themes from which Rand would subsequently develop Objectivism, including reason, property rights, individualism, libertarianism, and capitalism and depicts what Rand saw as the failures of governmental coercion. Of Rand's works of fiction, it contains her most extensive statement of her philosophical system.

The book depicts a dystopian United States in which heavy industry companies suffer under increasingly burdensome laws and regulations. Railroad executive Dagny Taggart and her lover, steel magnate Hank Rearden, struggle against "looters" who want to exploit their productivity. They discover that a mysterious figure called John Galt is persuading other business leaders to abandon their companies and disappear as a strike of productive individuals against the looters. The novel ends with the strikers planning to build a new capitalist society based on Galt's philosophy.

Atlas Shrugged received largely negative reviews, but achieved enduring popularity and ongoing sales in the following decades. The novel has been cited as an influence on a variety of libertarian and conservative thinkers and politicians. After several unsuccessful attempts to adapt the novel for film or television, a film trilogy was released from 2011 to 2014 to negative reviews; two theatrical adaptations have also been staged.

Atlas Shrugged is set in a dystopian United States at an unspecified time, in which the country has a "national legislature" instead of Congress and a "head of state" instead of a president. The United States appears to be approaching an economic collapse, with widespread shortages, business failures, and decreased productivity. Writer Edward Younkins said, "The story may be simultaneously described as anachronistic and timeless. The pattern of industrial organization appears to be that of the late 1800s—the mood seems to be close to that of the depression-era 1930s. Both the social customs and the level of technology remind one of the 1950s".

Many early 20th-century technologies are available, but later technologies such as jet planes and computers are largely absent. There is very little mention of historical people or events, not even major events such as World War II. Aside from the United States, most countries are referred to as "People's States" that are implied to be either socialist or communist.

Dagny Taggart, the operating vice-president of Taggart Transcontinental Railroad, keeps the company going amid a sustained economic depression. As economic conditions worsen and government enforces statist controls on successful businesses, people repeat the cryptic phrase "Who is John Galt?" which means: "Don't ask questions nobody can answer."

Her brother Jim, the railroad's president, seems to make irrational decisions, such as buying from Orren Boyle's unreliable Associated Steel. Dagny is also disappointed to discover that the Argentine billionaire Francisco d'Anconia, her childhood friend and first love, is risking his family's copper company by constructing the San Sebastián copper mines, even though Mexico will probably nationalize them.

Despite the risk, Jim and Boyle invest heavily in a railway for the region while ignoring the Rio Norte Line in Colorado, where entrepreneur Ellis Wyatt has discovered large oil reserves. Mexico nationalizes the mines and railroad line, but the mines are discovered to be worthless. To recoup the railroad's losses, Jim influences the National Alliance of Railroads to prohibit competition in prosperous areas such as Colorado. Wyatt demands that Dagny supply adequate rails to his wells before the ruling takes effect.