3 lives in this collection worked in non-euclidean geometry, from 1792 to today. Each has a full course on their life and the mathematics and physics they made.
Often together with: geometry. All fields
Kazan mathematician who published the first non-Euclidean (hyperbolic) geometry in 1829 and was rector of Kazan University for nineteen years.
geometry, non-euclidean geometry, analysis
Hungarian army engineer who independently discovered hyperbolic geometry and published it in 1832 as the Appendix to his father's Tentamen, together with an absolute geometry valid with or without the parallel postulate.
geometry, non-euclidean geometry, foundations of mathematics
Italian geometer who gave the first models of Lobachevsky's hyperbolic geometry, proving it as consistent as Euclid's, and whose name survives on the Laplace–Beltrami operator.
differential geometry, non-euclidean geometry, mathematical physics