The term Greek Mathematician refers to two of the most influential mathematicians in history, Euclid and Pythagoras. Euclid was an ancient Greek mathematician, often referred to as the 'Father of Geometry'. He is best known for his work on geometry, which includes the Elements, a collection of 13 books that laid the foundations of modern geometry. Pythagoras was another ancient Greek mathematician who is credited with discovering the Pythagorean theorem. He is also known for his contributions to number theory, music theory, and philosophy.