Thirtleby is a hamlet in the civil parish of Coniston, in the East Riding of Yorkshire, England. It is situated approximately 6 mi north-east of Hull city centre and 1 mi west of the village of Sproatley. Thirtleby was formerly a township in the parish of Swine, in 1866 Thirtleby became a separate civil parish, on 1 April 1935 the parish was abolished and merged with Coniston. In 1931 the parish had a population of 55.