James Pierson Beckwourth (April 26, 1798/1800 – October 20, 1866) was an American fur trapper, rancher, businessman, explorer, author and scout. Known as "Bloody Arm" because of his skill as a fighter, Beckwourth was of multiracial descent, being born into slavery in Frederick County, Virginia. He was eventually emancipated by his enslaver, who was also his father, and apprenticed to a blacksmith so that he could learn a trade.

As a young man, Beckwourth moved to the Western United States, first making connections with fur traders in St. Louis, Missouri. As a mountain man, he lived with the Crow people for several years. He is credited with the discovery of Beckwourth Pass, the lowest pass through the Sierra Nevada, connecting Reno, Nevada, and Portola, California during the California Gold Rush. He improved the Beckwourth Trail, which thousands of settlers followed to central California. Beckwourth narrated his life story to Thomas D. Bonner, who was described as "an itinerant justice of the peace", but was also a temperance speaker and journalist, who, according to his preface, by chance was present in Beckwourth's rustic California hotel when he decided to dictate his memoirs. The book was published in New York City and London in 1856 as The Life and Adventures of James P. Beckwourth: Mountaineer, Scout and Pioneer, and Chief of the Crow Nation of Indians. A translation appeared in France in 1860.

The reliability of Beckworth's autobiography was called into question from the beginning; an editor of it quoted the observation "that some one said of him that some men are rarely worthy of belief, but that Jim was always Beckwourthy of un-belief." "I knew Jim intimately and he was the biggest liar that ever lived." A review when it appeared called it "half fiction":

[P]arts of the tale smack of the "fish story." Mr. Beckwourth, or his narrator, has it all his own way, and we can fancy a lurking smile at the thought how glibly he puts together such a discordant mass of material brought out from the storehouse of memory, where there is no one at hand positively to contradict him.

Elinor Wilson has defended Beckwourth's narration as a valuable source of social history, especially for life among the Crow, although not all its details are reliable or accurate. The civil rights movement of the 1960s celebrated Beckwourth as an early African-American pioneer. He has since been featured as a role model in children's literature and textbooks.

James Beckwith was born into slavery in April 26, 1798 (or 1800), in Frederick County, Virginia. Of multiracial descent, his father was Jennings Beckwith, a white planter, and his mother was a Black woman enslaved by Jennings. Jennings was the son of Sir Marmaduke Beckwith, 3rd Baronet, who had immigrated to Virginia and worked as a merchant. Jennings reportedly had thirteen children with James' mother.

Jennings moved to Missouri around 1809, when James was young, taking James' mother and all her children with him. Although Beckwith acknowledged and raised his mixed-race children as his own, he legally held them as owner. His father arranged to apprentice him to a blacksmith so that he could learn a good trade. At age 19, he was fired by the artisan after getting into an argument with him. His father freed Beckwourth by manumission, by deed of emancipation in court in 1824, 1825, and 1826.

As a young man in 1824 Beckwourth joined General William Ashley's Rocky Mountain Fur Company. He worked as a wrangler during Ashley's expedition to explore the Rocky Mountains. In the following years, Beckwourth became known as a prominent trapper and mountain man. In July 1825, rendezvous, trapper and colleague Caleb Greenwood told the campfire story of Beckwourth's being the child of a Crow chief. He claimed Beckwourth had been stolen as a baby by raiding Cheyenne and sold to whites. This lore was widely believed, as Beckwourth had adopted Native American dress and was taken by some people as an Indian.