I'll take the bait.
Cannibalism: Ritual cannibalism of those who die of natural causes, especially one's own ancestors, was (and perhaps is) a venerated custom of some tribal societies of Africa and the Pacific Islands. I cannot call such a custom, where no sentient is actually harmed, an evil.
There are arguments to be made (though I won't make them) that killing to survive is not evil, and thus the hunting/killing mode of cannibalism would not be evil under those circumstances where there is not a sufficent supply of other edibles to support the local population or where they do not have access to another source of specific nutrients that can be found in human flesh, would also not be evil, under those specific circumstances.
Human sacrifice: If the sacrifice is willing, and gives themself in the sincere belief that they are dying to save their people, then the practice cannot be considered evil. This is, at least according to some historical sources, the model under which much (but not all) human sacrifice was practiced by the druids, and possibly by the Aztec as well. In addition, the Aztecs truly believed the sun would cease to rise if not fed, and the Celts believed tha under certain circumstances all their people would die because of prolonged winter, blight, or drought. Thus their sacrifices were intended to ensure their survival. Again, killing to to survive. On the other hand there was certainly much unwilling sacrifice in human history, and the depraved practice of human sacrifice to dark entities in a plea for personal power is certainly evil, if and when it occurs.