However, in all of these cases that I can think of, the other half is always human.
Are there any non-human hybrid characters? Especially ones that are recurring or at least the focus of an episode?
If not, is there an out-of-universe explanation for their absence/rarity/scarcity? From a fandom point of view, I can’t imagine a half-Klingon half-Vulcan might not make for an interesting story, for example.