HMS Onslow was an O-class destroyer of the Royal Navy. The O-class were intermediate destroyers, designed before the outbreak of the Second World War to meet the likely demands for a large number of destroyers. They had a main gun armament of four 4.7 in (120 mm) guns, and had a design speed of 36 kn (41 mph; 67 km/h). Onslow was ordered on 2 October 1939 and was built by John Brown & Company at their Clydebank, Glasgow shipyard, launching on 31 March 1941 and completing on 8 October 1941.

Onslow served with the Home Fleet during the war, with a major activity being escorting Arctic Convoys to the Soviet Union. She sank the German submarine U-589 in September 1942 and in December that year took part in the Battle of the Barents Sea, while escorting Convoy JW 51B to Russia. The convoy escorts held off attacks from the powerful cruiser Admiral Hipper, with Onslow being severely damaged and her captain, Robert Sherbrooke, seriously injured. She also saw detached service in the Mediterranean, covering the Malta Convoy Operation Harpoon in June 1942, and protected invasion shipping in the English Channel from German attack during the Normandy landings in mid-1944.

The ship was sold to the Pakistan Navy in 1948 and was renamed Tippu Sultan. Tippu Sultan was converted to a Type 16 anti-submarine frigate from 1957 to 1959 and took part in the 1965 and 1971 wars with India, remaining in service until 1980.

The O-class (and the following P-class) were designed the war to meet the Royal navy's need for large numbers of destroyers in the event of war occurring. They were an intermediate between the large destroyers designed for fleet operations (such as the Tribal-class destroyer) and the smaller and slower Hunt-class escort destroyers.

Onslow was 345 ft (105.16 m) long overall, 337 ft (102.72 m) at the waterline and 328 ft 9 in (100.20 m) between perpendiculars, with a beam of 35 ft (10.67 m) and a draught of 9 ft (2.74 m) mean and 13 ft 6 in (4.11 m) full load. Displacement was 1,610 long tons (1,636 t) standard and 2,200 long tons (2,235 t) full load. Two Admiralty three-drum boilers fed steam at 300 psi (2,100 kPa) and 620 °F (327 °C) to two sets of Parsons single-reduction geared steam turbines which drove two propeller shafts. The machinery was rated at 40,000 shp (30,000 kW) giving a maximum speed of 36.75 kn (42.3 mph; 68.1 km/h), corresponding to 33 kn (38 mph; 61 km/h) at deep load 500 long tons (508 t) of oil was carried, giving a radius of 3,850 nmi (4,430 mi; 7,130 km) at 20 kn (23 mph; 37 km/h). Onslow was configured as a leader for a destroyer flotilla, and as such had a crew of 217 officers and men.

Onslow had a main gun armament of four 45-calibre 4.7-inch (120 mm) Mark IX guns in single mounts. The ship was designed to carry two quadruple 21-inch (533 mm) torpedo tubes, but early experience of the vulnerability of destroyers to air attack off Norway and during the evacuation from Dunkirk in 1940 resulted in the armament of the O-class being revised during construction, with the aft set of torpedo-tubes removed and replaced by a 4-inch (102 mm) QF Mark V anti-aircraft gun, although the 4-inch gun was later removed and the second bank of torpedo tubes re-instated. Onslow was completed with a close-in anti-aircraft armament of one quadruple 2-pounder "pom-pom" mount together with four Oerlikon 20 mm cannon, with two on the bridge wings and two further aft, abreast the searchlight platform. After April 1943, the single Oerlikon mounts abreast the searchlights were replaced by twin mounts. Four depth charge throwers were fitted, with 60 depth charges carried.

Onslow was refitted and rearmed in 1948 as part of her sale to Pakistan. More modern fire control equipment was fitted and the Oerlikons were replaced by Bofors 40 mm anti-aircraft guns, with a twin Bofors 40 mm mount replacing the quadruple pom-pom. Between 1957 and 1959, the ship was refitted as a Type 16 frigate, which resulted in a revised armament being fitted. A twin 4-inch gun was mounted forward with a close-in anti-aircraft armament of five Bofors 40 mm guns (one twin and three singles). Anti-submarine armament consisted of two Squid anti-submarine mortars, while a quadruple set of 21-inch torpedo tubes were fitted.

The ship was ordered as part of the Second Emergency Flotilla as Packenham on 2 October 1939, at a contract price of £416,770 (excluding government provided equipment such as armament), and was laid down at John Brown & Company's Clydebank shipyard on 1 July 1940. In early 1941, the ship swapped names with the destroyer Onslow, also under construction, and was launched as Onslow on 31 March 1941. Onslow was damaged by a bomb during an air raid on 3 June 1941, delaying completion by about a month. Onslow commissioned on 23 September 1941, with construction completing on 8 October 1941. She was the second ship named Onslow to commission with the Royal Navy.