In Episode 70 of the original Star Trek television series, entitled "Let That Be Your Last Battlefield", two characters are Cheronians -- people who are black on one side and white on the other, with a line down the middle -- loathe one another. One thinks the other inferior; one thinks the other is an oppressor. It turns out that, while they appear identical to the crew of the Starship Enterprise, one is white on the left and the other is black on the left. Out of this difference, the Cheronians have constructed a basis for hating one another.