Mercator was a 16th Century cartographer best known for inventing the Mercator projection. You can read more about Mercator on Wikipedia:
And here are a few related books that may be of interest:
For the serious scholar of cartography, you’ll want to check out the History of Cartography series by J.B. Harley and David Woodward. There are several volumes including Cartography in the European Renaissance: Part 1 and Part 2.
Thanks to everyone who voted and submitted nominees! Stay tuned for the 3rd inductee!