Isaac Purdy (May 22, 1804 - September 1852) was a British hydrographer and engraver active in the second quarter of the 19th century. Purdy was born in Middlesex, England, the son of a gunsmith and the nephew of the cartographer and hydrographer John Purdy. He worked for the firm of Richard Holmes Laurie as an engraver and hydrographer before transitioning to the Admiralty sometime in 1851. Several nautical charts from the 1840s and as late as 1851, bear his imprint. He should not be confused with Isaac Purdy 2 (fl. c. 1840 - 1869), a relative and also a hydrographer.