The Dalton Gang, also known as The Dalton Brothers, was a family of both lawmen and outlaws in the American Old West during 1890-1892. They specialized in bank and train robberies. They were related to the Younger brothers, who rode with Jesse James, though they acted later and independently of the James-Younger Gang. The three Dalton brothers involved in the gang were Gratton "Grat" Dalton (b. 1861), Bob Dalton (b. 1869), and Emmett Dalton (b. 1871). A fourth brother, William M. "Bill" Dalton (1866–1894), also had a career as an outlaw, but operated as a member of the Wild Bunch.

Lewis Dalton, father of the outlaws, was from Jackson County, Missouri. He was a saloon keeper in Kansas City, Kansas, when he married Adeline Younger, an aunt of Cole and Jim Younger. By 1882, the family was living in the Indian Territory, now the state of Oklahoma. A few years later, they had settled down in Coffeyville in southeastern Kansas. Lewis and Adeline Dalton had a total of 15 children, 2 of whom died in infancy.