The Hawthorn M (or Mansfield) Class were a class of two destroyers built for the Royal Navy under the pre-war 1913-14 Programme for World War I service.

Class overview
Builders	Hawthorn Leslie and Company, Hebburn
Operators	Royal Navy
Built	1914–1915
In commission	1915–1921
Completed	2
Retired	2
General characteristics
Type	Destroyer
Displacement	1,057 long tons (1,074 t)
Length	271 ft 6 in (82.75 m) o/a
Beam	27 ft 6 in (8.38 m)
Draught	10 ft 6 in (3.20 m)
Depth	16 ft 9 in (5.11 m)
Propulsion	Yarrow-type boilers, Parsons I.R. steam turbines, 3 shafts, 27,000 hp (20,134 kW), 300 tons oil fuel
Speed	35 knots (40 mph; 65 km/h)
Complement	76
Armament	3 × QF 4 in (102 mm) Mark IV guns, mounting P Mk.IX 1 × single QF 2-pounder "pom-pom" Mk.II 2 × twin 21 inch (533 mm) torpedo tubes

They were similar to the Admiralty M class, but completed to a modified design by Hawthorn Leslie and Company, Hebburn on Tyne. They had four funnels instead of the three funnels of the Admiralty design; as a consequence, they were the last four-funnelled destroyers (apart from Leaders) to be built for the Royal Navy. The midships 4 inch gun was shipped between the second and third funnels. Both ships were laid down on 9 July 1914 and completed in 1915. Both survived the war and were scrapped in 1921,

Hawthorn Leslie subsequently received orders for two further M class destroyers as part of the large batch of orders placed in May 1915, but these two - Pidgeon and Plover - were built to the Admiralty M class design.