HMS Monarch was a 74-gun third rate ship of the line of the Royal Navy, built by Adam Hayes and launched on 20 July 1765 at Deptford Dockyard.

She fought in the van of Graves' fleet at the Battle of the Chesapeake in 1781 under Admiral Francis Reynolds.

[2] Later in 1795 she was part of the small fleet under Admiral George Elphinstone that captured the Cape of Good Hope from the Dutch East India Company at the Battle of Muizenberg.

In 1797 Monarch was Vice Admiral Richard Onslow's flagship at the Battle of Camperdown, under Captain Edward O'Bryen In 1801 Monarch was part of Admiral Nelson's fleet at the Battle of Copenhagen, where her captain, James Robert Mosse was killed early in the action and replaced by Lieutenant John Yelland, the next highest ranking officer.

[3] In 1807, Monarch helped escort the Portuguese royal family in its flight from Portugal to Brazil.