Isaac Benson Lucas, KC (September 19, 1867 – March 8, 1940) was a Canadian lawyer and politician.

He served as a Conservative Member of the Legislative Assembly of Ontario for Grey Centre from 1898 to 1919.

He graduated from Osgoode Hall in 1899 and entered practice in Owen Sound, later moving to Markdale.

During his time in office, Lucas was responsible for steering the Workmen's Compensation Act through the provincial legislature.

He also served as government representative on the Hydro-Electric Commission and helped promote the development of a park in the area surrounding the Horseshoe Falls at Niagara.