HMS Forfar (F30) was a British ocean liner that was commissioned into the Royal Navy as an armed merchant cruiser in 1939 and sunk by enemy action in 1940. She was launched in Scotland in 1920 as a transatlantic liner for the Canadian Pacific Steamship Company as Montrose. She was one of three sister ships. The others were Montcalm, also launched in 1920, and Montclare, launched in 1921.

The Fairfield Shipbuilding and Engineering Company, Limited, was a Scottish shipbuilding company in the Govan area on the Clyde in Glasgow. Fairfields, as it is often known, was a major warship builder, turning out many vessels for the Royal Navy and other navies through the First World War and the Second World War. It also built many transatlantic liners, including record-breaking ships for the Cunard Line and Canadian Pacific, such as the Blue Riband-winning sisters RMS Campania and RMS Lucania. At the other end of the scale, Fairfields built fast cross-channel mail steamers and ferries for locations around the world. These included ships for the Bosporus crossing in Istanbul and some of the early ships used by Thomas Cook for developing tourism on the River Nile.