Pecos Bill, legendary cowboy hero of the American Southwest, who personified the frontier virtues of strength, courage, ingenuity, audacity, and humor. His story comprises a series of superhuman feats that illustrate these virtues.

Pecos Bill is said to have been born in Texas in the 1830s. According to lore, as an infant he used a bowie knife as a teething ring and played with bears and other wild animals. After falling out of his parents' wagon near the Pecos River in Texas, he became lost and was subsequently raised by coyotes. As an adult, he rode a mountain lion and used a rattlesnake as a whip. Later he rode a horse named Widow-Maker, which no one else could ride—not even Bill's bride, Slue-Foot Sue, whom he met when she rode down the Río Grande on a catfish as large as a whale. During a dry year, Pecos Bill drained the Río Grande to water his ranch, which included the entire state of New Mexico.

The original "Saga of Pecos Bill" was written in 1923 by Edward O'Reilly for The Century Magazine. Later writers either borrowed tales from O'Reilly's article or added further adventures of their own invention to the cycle. Since O'Reilly's time, Pecos Bill has been celebrated in countless publications and in two motion pictures: Melody Time (1948) and Tall Tale: The Unbelievable Adventures of Pecos Bill (1995). Although O'Reilly claimed that cowboys told Pecos Bill stories, students of folklore have been unable to authenticate any oral accounts of Pecos Bill among cowboy storytellers. Despite his enduring appeal for American readers as a symbol of the wild West, the legend of Pecos Bill is more a product of popular culture than of folklore.