William Dunn (April 28, 1834 – March 18, 1902) was a sailor in the U.S. Navy during the American Civil War.

Dunn volunteered for service in the U.S. Navy and was assigned to the Union monitor USS Monadnock (1863).

On January 15, 1865, the North Carolina Confederate stronghold of Fort Fisher was taken by a combined Union storming party of sailors, marines, and soldiers under the command of Admiral David Dixon Porter and General Alfred Terry.

Monadnock in action during several attacks on Fort Fisher, North Carolina, 24 and 25 December 1864; and 13, 14, and 15 January 1865.

With his ship anchored well inshore to insure perfect range against the severe fire of rebel guns, Quartermaster Dunn continued his duties when the vessel was at anchor, as her propellers were kept in motion to make her turrets bear, and the shooting away of her chain might have caused her to ground.