Lt. Col. William Robertson was a military person, merchant and political figure in Nova Scotia.
He represented Annapolis Township in the Nova Scotia House of Assembly from 1808 to 1811.
He was a United Empire Loyalist of Scottish descent and settled at Annapolis Royal, Nova Scotia.
He was elected to the provincial assembly in an 1808 by-election held after Thomas Walker was unseated.
He is buried in the Garrison Cemetery (Annapolis Royal, Nova Scotia).