TS Queen Mary is a Clyde steamer launched in 1933 at the William Denny shipyard, Dumbarton, for Williamson-Buchanan Steamers. She is currently being restored as a museum ship, in Glasgow.

TS Queen Mary originally measured 871 gross registered tons and was powered by three direct drive steam turbines built by Parsons Marine Steam Turbine Company. The vessel held a passenger certificate for 2,086 passengers, later reduced to 1,820.

Following the completion of her trials during which a maximum speed of 19.7 knots (36.5 km/h) was achieved on the Skelmorlie measured mile, she joined Williamson-Buchanan's fleet on 20 May 1933.

Williamson-Buchanan based TS Queen Mary at Glasgow's Bridge Wharf, where she carried approximately 13,000 passengers each week.

TS Queen Mary sailed during the summer season for the Arran coast, or for the Kyles of Bute.^{[citation needed]}

In 1935, Cunard Line asked Williamson-Buchanan to change the name of TS Queen Mary to TS Queen Mary II, in order to make the name available for their new flagship liner, which was due to be launched by Queen Mary. The owners of Williamson-Buchanan agreed and in exchange, Cunard Line presented them with a portrait of Her Majesty to hang in the forward lounge of the steamer.^{[citation needed]}

In 1936, the entire Williamson-Buchanan fleet, including TS Queen Mary II, passed into the ownership of the London, Midland and Scottish Railway Company. Later that same year she joined Williamson-Buchanan Steamers (1936) Ltd.^{[citation needed]}

During World War II the steamer provided a mail and passenger service to the Scottish Islands.