William Cottnam Tonge (April 29, 1764 – August 6, 1832) was a judge and political figure in Nova Scotia.
Tonge also was named a justice of the peace and served as judge in the Inferior Court of Common Pleas for Hants County.
Although he was able to secure some military contracts, his attempts to improve his finances through patronage were blocked by the lieutenant governor John Wentworth.
Tonge became the centre of a dispute between the lieutenant governor and the assembly over control of expenditures in the province in the legislative session that followed.
Later that year, George Prevost, the new lieutenant governor, named Tonge deputy commissary general for the Invasion of Martinique (1809).