| William Earnshaw | |
| Birth Date: | 12 April 1828 |
| Birth Place: | Chester, Pennsylvania |
| Death Place: | Dayton, Ohio |
| Placeofburial: | Woodland Cemetery and Arboretum Dayton, Ohio |
| Placeofburial Label: | Place of burial |
| Allegiance: | United States of America Union |
| Branch: | United States Army Union Army |
| Serviceyears: | 1861–1867 |
| Rank: | chaplain |
| Unit: | 49th Pennsylvania Infantry U.S. Volunteers, Hospital Chaplain |
| Battles: | American Civil War |
| Laterwork: | 8th Commander-in-Chief, Grand Army of the Republic |
William Earnshaw, D.D. (April 12, 1828 – July 7, 1885) was an American minister who served in the Union Army as a chaplain and as the 8th Commander-in-Chief of the Grand Army of the Republic, 1879-1880.
Earnshaw was born on April 12, 1828, in Chester, Pennsylvania. Soon after the outbreak of the Civil War, he enlisted April 16, 1861, as a private in the 49th Pennsylvania Infantry and was mustered in as the regiment's chaplain with the rank of captain. Earnshaw resigned his commission on October 12, 1862, when the regiment was consolidated with another regiment. He was appointed a hospital chaplain in the U.S. Volunteers April 22, 1863, and remained in the service until August 27, 1867.
With the necessity of creating national cemeteries, Ernshaw was superintendent of the construction of Stones River National Cemetery and Nashville National Cemetery. He was elected chaplain of the National Military Home in Dayton, Ohio, on September 5, 1867, and held the post until illness forced him to retire.
Earnshaw was Commander of the Ohio Department, Grand Army of the Republic in 1876, Junior Vice-Commander in 1877, and presided at the national encampment of the G.A.R. in Albany, New York, in 1879, when he was elected to serve as the national organization's 8th Commander-in-Chief.
He died July 7, 1885, in Dayton, Ohio, and is buried there in Woodland Cemetery and Arboretum.