Bolyai and Lobatschevsky
euclids elements
'Elements' was written by Euclid.
compositions
euclids elements
There are 13 books in Euclid's Elements.
Regular solids
euler
Archimedes
john graunt
pythogoras
Yes. There were mathematicians who were in geometry. In fact, anyone who contributed to our understanding of geometry was a mathematician.
Probably all mathematicians, from very ancient times.