Joseph Kay (1775 - 1847) was an English architect, particularly active in the early years of the 19th century, and associated with the layout of central Greenwich and with Hastings. He was one of the original members of the Royal Institute of British Architects, and was elected a fellow in 1834.
Kay was a pupil of Samuel Pepys Cockerell, and studied European architecture during a trip (1802-1805) alongside Robert Smirke. In 1807, he married Sarah Henrietta Porden (1785-1859), the eldest daughter of architect William Porden; he was assistant to Porden during the building of the second Eaton Hall near Chester, Cheshire (1804–1812). One of his earliest work in his own right was interior design of the Assembly Rooms in Clifton, Bristol, c.1811.
In London, as surveyor to the Foundling Hospital, he designed houses on the east side of Mecklenburgh Square (1810–21), and, as clerk of works to Greenwich Hospital, he remodelled the town centre (creating Nelson Street, College Approach and the Market) in Greenwich (1829); the nearby Trafalgar Tavern (1837) is also his work. In Edinburgh he designed the Post Office in Waterloo Place. His masterpiece was Pelham Crescent with the Church of St Mary-in-the-Castle in the centre, in Hastings, Sussex (1824–1828), built for Thomas Pelham, 2nd Earl of Chichester; Colvin described it:
Other buildings by Kay in Hastings also survive, including Belmont House.