Thomas Mackay (1849 – 1912) was a British wine merchant and classical liberal.
Mackay, the son of a colonel, was born in Edinburgh and educated at Glenalmond and New College, Oxford. He was called to the bar in 1879 but left to enter the wine trade because he felt that he was not earning enough to support his wife and family. He retired ten years later in order to campaign for liberalism.
He criticised old age pensions because he believed they would harm character and advocated reducing "the encouragement to pauperism held out by our present system of out-door relief" by restoring independence. Also, Mackay did not favour a compromise between individualism and socialism: "Those who talk of compromise seem not to realize that the knell of the period of compromise has sounded...We are falling under a tyranny more absolute and unrelenting than anything the world has ever seen".