Ben Kilpatrick was an American outlaw during the closing years of the American Old West. He was a member of the Wild Bunch gang led by Butch Cassidy and Elzy Lay. He was arrested for robbery and served about 10 years of his 15-year sentence. Upon his release from prison, he returned to crime and was killed by a hostage during a train robbery.

Butch Cassidy's Wild Bunch was one of the loosely organized outlaw gangs operating out of the Hole-in-the-Wall, near Kaycee in Wyoming, a natural fortress of caves, with a narrow entrance that was constantly guarded. In the beginning, the gang was referred to as the "Hole in the Wall Gang" during the Old West era in the United States. It was popularized by the 1969 movie, Butch Cassidy and the Sundance Kid, and took its name from the original Wild Bunch. The gang was led by Butch Cassidy, and it included his closest friends Elzy Lay, the Sundance Kid, Tall Texan, News Carver, Camilla "Deaf Charley" Hanks, Laura Bullion, Flat-Nose Curry, Kid Curry, and Bob Meeks. They were the most successful train-robbing gang in history.