Isaac W. Sprague (May 21, 1841 - January 5, 1887) was an American sideshow attraction. His stage name was The Skeleton Man. He also appeared as The Living Skeleton and The Original Thin Man. He was born in Massachusetts. Doctors were puzzled when he began losing weight rapidly in his teens. He joined a sideshow in 1865, then got a job at P. T. Barnum's American Museum in New York City in 1868. He married and had three healthy sons. He died penniless in Chicago, Illinois in 1887.