Herbert Spencer

Herbert Spencer, towards the end of the 19th century.
Spencer coined the phrase "survival of the fittest", a phrase that Charles Darwin never used. Darwin was concerned with natural evolution, whereas Spencer wanted to apply natural selection to society. The name "Herbert Spencer" is often associated with Social Darwinism (again nothing to do with Darwin) but, to be fair, it wasn't quite the Social Darwinism used by the Nazis. They subscribed to what, in Spencer's time, was called Reform Darwinism, which promoted  eugenics programs and segregation imposed by the state. Spencer wasn't described as a Social Darwinist until the 1930s, and it's probably not a coincidence that the Nazis, and fascists elsewhere, started to gain prominence about then.

Original B&W photo.