Mercator, Gerardus, muhr KAY tuhr, juhr AHR duhs (1512-1594), was a Flemish geographer who became the most important mapmaker of the 1500's. He won lasting fame because of his world map of 1569. It introduced a new way of showing the roughly ball-shaped earth on a flat sheet of paper. This method, called the Mercator projection, is still used today.