Felix Klein
25 April 1849 — 22 June 1925
Felix Christian Klein was a German mathematician, mathematics educator and historian of mathematics, known for his work in group theory, complex analysis, non-Euclidean geometry, and the associations between geometry and group theory. His 1872 Erlangen program classified geometries by their basic symmetry groups and was an influential synthesis of much of the mathematics of the time.
A memorial on Digital Cemetery, an endless map you can explore. This grave stands at coordinates 6, 14.