William Ambrosia Cowley (fl. c. 1683 - 1686) was an English privateer and navigator notable for circumnavigating the globe and for producing the first map of the Galapagos Islands, drafted in 1684. A brief account of his travels appeared as 'Cowley's Voyage Round the Globe' in William Hacke's Collection of Original Voyages, published in 1699. He was also the originator of the phantom island of Pepys, supposedly some 230 nautical miles north of the Falkland Islands.