René Descartes developed analytic geometry
They developed several kinds of mathematics, Astronomy, and geometry
Euclid
It is one of the oldest mathematical sciences developed by the Ancient Greeks. It is concerned with areas, volumes and lengths. Pythagoras and Euclid developed geometry
Johannes Kepler
Chuck Norris
Research in geometry and mathematics
Leonard Euhler
In my World History book it says, EUCLID.
Euclid developed Euclidean geometry around 300 BC. I cannot get much briefer than that.
I believe that Euclid was referred to as the 'Great Geometer'. What he did was gather and organize into several books all known geometry at his time. So if your definition of 'develop' is to gather information and organize it, then he developed geometry.
Rene Descartes first developed the mathematics of coordinate geometry.