Robert Lyon (July 6, 1829 - March 21, 1888) was a lawyer, politician and judge in the County of Carleton in eastern Ontario. He was mayor of Ottawa in 1867 and a Liberal member of the Legislative Assembly of Ontario from 1867 to 1871. His father, George Lyon, was a Scottish captain in the British army, who settled in Richmond, Ontario. His oldest brother was George Byron Lyon, another mayor of Ottawa. Robert was born in the village of Richmond in 1829.