Everyone knows about Charles Darwin, but hardly anyone remembers Alfred Russel Wallace, who came up with the idea of natural selection at the same time as Darwin. Darwin’s publication of the On the Origin of Species was spurred on by Wallace. Flora Lichtman and Sharon Shattuck shed a little light on Wallace with this video:
Indeed, from the introduction of On the Origin of Species:
I have more especially been induced to [publish], as Mr. Wallace, who is now studying the natural history of the Malay archipelago, has arrived at almost exactly the same general conclusions that I have on the origin of species. Last year he sent to me a memoir on this subject, with a request that I would forward it to Sir Charles Lyell, who sent it to the Linnean Society, and it is published in the third volume of the Journal of that Society. Sir C. Lyell and Dr. Hooker, who both knew of my work—the latter having read my sketch of 1844—honoured me by thinking it advisable to publish, with Mr. Wallace’s excellent memoir, some brief extracts from my manuscripts.
— Darwin, 1859. On the Origin of Species.