Eugenio Beltrami
He is primarily known today for his last publication, in 1733 shortly before his death. Now considered the second work in non-Euclidean geometry, "Euclides ab omni naevo vindicatus" ("Euclid Freed of Every Flaw") languished in obscurity until it was rediscovered by Eugenio Beltrami, in the mid-19th century.