The Bellona-class ships of the line were a class of five 74-gun third rates, whose design for the Royal Navy by Sir Thomas Slade was approved on 31 January 1758. Three ships were ordered on 28 December 1757, with names being assigned on 1 February 1758. Two further ships to this design were ordered on 13 December 1758, at the same time as two ships of a revised design – the Arrogant Class.
Slade's Bellona class was the first class of British 74s to have a gun deck length of 168 ft (51 m), and marked the beginning of a stabilisation of the design of this size of ship. Several subsequent classes designed by Slade were almost identical to the Bellona draught, with the main differences restricted to the underwater hull – the most numerous of these being the Arrogant and Elizabeth classes.