William Sweeney (born 1856, date of death unknown) was a United States Navy sailor and a recipient of the United States military's highest decoration, the Medal of Honor. Born in 1856 in Boston, Massachusetts, Sweeney joined the Navy from that state. By June 15, 1880, he was serving as a landsman in the engineering department of the USS Jean Sands. On that night, while Jean Sands was outside the Norfolk Naval Shipyard, he and another sailor, Landsman James F. O'Conner, jumped overboard and rescued a young girl from drowning. For this action, both Sweeney and O'Conner were awarded the Medal of Honor four years later, on October 18, 1884.