As in much mid-century science fiction influenced by H.G. Wells (who was such a fervent eugenicist that Sir Francis Galton made fun of his extremism), eugenics plays a role in Frank Herbert’s Dune.
Most famously, the female order who advise the Great Houses (rather like how Jesuits served as confessors to the Catholic monarchs) have been secretly directing for many generations an elite breeding program to produce an ubermensch who can see into the future.
But its manifestation in Dune’s main character Paul is far from an unmixed blessing. Paul is beset by the intuition that what he does to survive on Dune will launch a disastrous jihad across the 13,000 planets of the empire.
Interestingly, Paul intuits that the coming jihad will be for unplanned eugenics motivations, although not to further separate the races but to mix them:
Here was the race consciousness that he had known once as his own terrible purpose […] The race of humans had felt its own dormancy, sensed itself grown stale and knew now only the need to experience turmoil in which the genes would mingle and the strong new mixtures survive.