HMS Thetis was a 32-gun fifth-rate frigate of the Royal Navy, built by Wyatt & Co. at Buckler's Hard shipyard in 1773.

From 1777 to 1781 she served with the North American squadron.

In January, 1778 she was under the command of Capt.

[1] Thetis took part in the action of 9 August 1780, when a convoy she was escorting fell prey to a Franco-Spanish squadron.

55 merchantmen were captured, but she managed to escape.