HMS Monmouth was a 66-gun third-rate ship of the line of the Royal Navy, and was likely named for James, Duke of Monmouth. She served from 1667 to 1767, winning ten battle honours over a century of active service. She was rebuilt a total of three times during her career—each time effectively becoming a completely new ship.
She was built at Chatham Dockyard in 1667 by Phineas Pett II—seeing action whilst still in the Thames, during the Raid on the Medway, and fought at the Battle of Solebay in 1672, shortly followed by the Battle of Texel in 1673. She fought at the Battle of Barfleur in 1692. Monmouth underwent her first rebuild at Woolwich Dockyard in 1700, remaining a 66-gun ship. She fought at the Battle of Vigo Bay in 1702 under Admiral John Baker who was also captain at the Capture of Gibraltar and the Battle of Málaga in 1704.
In 1707, she had belonged to Admiral Sir Cloudesley Shovell's fleet. She saw action during the unsuccessful Battle of Toulon and was present during the great naval disaster off the Isles of Scilly when Shovell and four of his ships (Association, Firebrand, Romney and Eagle) were lost, claiming the lives of nearly 2,000 sailors. Monmouth suffered little to no damage and finally managed to reach Portsmouth.
Her second rebuild was carried out at Portsmouth Dockyard, where she was increased to a 70-gun ship built according to the 1706 Establishment, and relaunched on 3 June 1718. On 7 September 1739 Monmouth was ordered to be taken to pieces and rebuilt for what was to be the final time at Deptford according to the 1733 proposals of the 1719 Establishment. She was relaunched on 6 September 1742.
In 1747, she fought at Finisterre and Ushant. On 2 March 1747 Monmouth, Captain Henry Harrison, brought into Plymouth a French privateer of 20 carriage guns and eight swivel guns. The privateer was the Comte de Maurepas and capturing her required a chase of three days. At about the same time Monmouth captured the privateer Queen of Hungary.
In 1758 Monmouth captured the larger French ship Foudroyant. Monmouth was also present at Belle Île in 1761.
After a hundred years of service, she was finally broken up in 1767; a newspaper of the time gave her epitaph as