William Washington Larsen (August 12, 1871 – January 5, 1938) was a United States Representative from Georgia.

He taught school in 1895, studied law, gained admittance to the state bar in 1897 and became a practicing attorney in Swainsboro, Georgia.

In 1916, Larsen was elected as a Democrat to the 65th United States Congress representing Georgia's 12th congressional district.

He was a regional manager for the Farm Credit Administration headquarters in Columbia, South Carolina from 1933 until his resignation in 1936.

He won an appointment to the Georgia Unemployment Insurance Commission in 1937 and served until his death in Dublin on January 5, 1938.