A B movie is a low-budget commercial motion picture that is not definitively an arthouse or pornographic film. In its original usage, during the Golden Age of Hollywood, the term more precisely identified a film intended for distribution as the less-publicized, bottom half of a double feature. Although the U.S. production of movies intended as second features largely ceased by the end of the 1950s, the term B movie continued to be used in the broader sense it maintains today. In its post–Golden Age usage, there is ambiguity on both sides of the definition: on the one hand, many B movies display a high degree of craft and aesthetic ingenuity; on the other, the primary interest of many inexpensive exploitation films is prurient. In some cases, both may be true.

In either usage, most B movies represent a particular genre—the Western was a Golden Age B movie staple, while low-budget science-fiction and horror films became more popular in the 1950s. Early B movies were often part of series in which the star repeatedly played the same character. Almost always shorter than the top-billed films they were paired with, many had running times of 70 minutes or less. The term connoted a general perception that B movies were inferior to the more handsomely budgeted headliners; individual B films were often ignored by critics.

Big Mouth (Lakota: Itȟáŋka) (born 1822–died October 29, 1869) was an Oglala-born chieftain of the Brulé Lakota, highly regarded by the Brulé for his bravery and aggressive military leadership. He was one of the chiefs who signed the second Treaty of Fort Laramie in 1868 and remained a bitter opponent of further American settlement, ridiculing Spotted Tail and other Sioux chieftains upon their return from a mission to Washington, DC. He was sixth son of Old Chief Smoke (1774–1864) and twin brother of Blue Horse.

One of the principal chiefs at the Whetstone Agency, located along the Missouri River, where most of the Brulé and Oglala bands had gathered, Big Mouth gained increasing support for his stance among members of the tribe. He criticized what he described as Spotted Tail's reversal of Sioux policy, saying Spotted Tail had been entertained by American politicians and given a personal tour through the major cities of the east coast. Faced with increasing opposition to his leadership, Spotted Tail visited Big Mouth at his lodge, where, upon approaching the entrance, Big Mouth was seized by two warriors and held down while Spotted Tail shot and killed him.