William Ellis (c. 1834 – February 1, 1875) served in the Union Army during the American Civil War.

Ellis was born in England in about his official residence when he received his Medal of Honor was listed as Watertown, Wisconsin.

He died February 1, 1875, in San Bernardino County, California.

His award citation reads: The President of the United States of America, in the name of Congress, takes pleasure in presenting the Medal of Honor to First Sergeant William Ellis, United States Army, for extraordinary heroism on 14 January 1865, while serving with Company K, 3d Wisconsin Cavalry, in action at Dardanelles, Arkansas.

This article about a person of the American Civil War is a stub.