Alfred Russel Wallace. He famously proposed a version of evolution by natural selection independently of Darwin in 1858.

See their published 1858 papers here and Wallace Online.

For the truth behind the myth-laden story of Wallace and Darwin see:
John van Wyhe, Dispelling the Darkness. (2013)

Here the real historical Wallace is revealed, very different from the supposedly victimised forgotten hero figure of the fan literature devoted to him since the 1960s.

See: The Complete Photographs of Darwin