William Ahern (1861 – November 7, 1916) was a sailor in the United States Navy who received the Medal of Honor for valor during an engineering crisis that threatened his ship.

On July 1, 1897, he was serving aboard the USS Puritan as a watertender when the crown sheets on one of her boilers collapsed.

Puritan at the time of the collapse of one of the crown sheets of boiler E of that vessel, 1 July 1897.

Wrapped in wet cloths to protect his face and arms, William Ahern entered the fireroom, crawled over the tops of the boilers and closed the auxiliary stop valve, disconnecting boiler E and removing the danger of disabling the other boilers.In newspaper reports his name is given as "William O'Hearn": Chicago Tribune June 3, 1898; Oakland Tribune May 20, 1898; New York Times February 6, 1898.

[2] This article incorporates public domain material from Medal of Honor recipients Interim 1871-1898.