Vice Admiral Sir John Mennes (with variant spellings, 1 March 1599 – 18 February 1671) was an English naval officer, who went on to be Comptroller of the Navy.

He figures prominently in the Diary of Samuel Pepys, who reported directly to Mennes at the Navy Office and thought him an incompetent civil servant, but a delightful social companion.

[1] Educated at his local grammar school in Sandwich, and Corpus Christi College, Oxford, Mennes went to sea and in 1620 saw action off Dominica, fighting Spanish warships.

Pepys's kindest judgement on him (when he was wrongly thought to be dying in 1666) was that he was a "good, honest, harmless gentleman, but not fit for office".

Even Pepys was prepared in 1670 to defend Mennes in public before the House of Commons as a man of great integrity, who had worn out his health in the service of the Crown.

The publisher, Henry Herringman, stated that he collected the poems from "Sir John Mennis "[sic]" and Dr. Smith's drollish intercourses".

Another anthology, Wit Restored, appeared in 1658, with verse letters from Smith to Mennes, "then commanding a troop of horse against the Scots".