HMS Onslaught was a British Oberon-class attack submarine operated by the Royal Navy.

The Oberon class was a direct follow on of the Porpoise-class, with the same dimensions and external design, but updates to equipment and internal fittings, and a higher grade of steel used for fabrication of the pressure hull.

[2] Propulsion machinery consisted of 2 Admiralty Standard Range 16 VMS diesel generators, and two 3,000 shaft horsepower (2,200 kW) electric motors, each driving a 7-foot-diameter (2.1 m), 3-bladed propeller at up to 400 rpm.

[2] Onslaught was laid down by Chatham Dockyard on 8 April 1959, and launched on 24 September 1960.

This article about a specific naval submarine of the United Kingdom is a stub.