Thomas Marks (June 21, 1834 – July 9, 1900) was an Irish-born Canadian businessman who served as the first mayor of Port Arthur, Ontario (later part of Thunder Bay).
He was born in Kilfinane, the son of Samuel Marks, and came with his family to Bytown in Upper Canada in the 1840s.
He supplied contractors working on the railway and also established warehouses and docks on the waterfront.
He was reeve of Shuniah from 1875 to 1884 and became mayor of the newly incorporated town of Port Arthur in 1884.
His nephew George Thomas Marks also served as mayor of Port Arthur.