John Sleath (1767–1847) was an English cleric and High Master of St Paul's School, London.
In 1784 he went up as a Rugby exhibitioner to Lincoln College, Oxford, but in 1785 was elected to a scholarship at Wadham.
On 16 June 1814 Sleath was appointed High Master—headmaster—of St Paul's School, and was in post to 10 October 1837.
The university entrance results for his pupils were good, with Benjamin Jowett being among them, and nine fellows of Trinity College, Cambridge.
[3] Sleath was made prebendary of Rugmere in St Paul's Cathedral, 5 July 1822; chaplain in ordinary to King George in 1825; subdean of the Chapel Royal, St James's, 28 June 1833; rector of Thornby, Northamptonshire, in 1841.