* OlderThanFeudalism: A special mention to Zeus/Jupiter in [[GreekMythology Greek]] and Roman mythology: not only is he an unfaithful god who seduces human women, he takes the appearance of various animals (swan, bull (!), a [[HaveAGayOldTime shower of gold]], etc.) to do so.
** The wife of the King of Minos mated with a sacrificial bull sent by the gods and gave birth to the minotaur. This was as punishment for Minos refusing to sacrifice it.
** Centaurs love this trope, in both behavior and origins.
** Satyrs constantly go after human and/or nymph women.
* In many myths, demons are unable to breed naturally, and must instead mate with a human, producing a demonic offspring. Hence the Incubi, Succubi, and various other HornyDevils.
* The Hippogriff, half-horse, half griffin. As griffins eat horses according to mythology, it was seen as a metaphor for a impossibly improbable thing, especially since the Hippogriff was never believed in, even at a time when griffins themselves were believed in.
* To avoid paying for the construction of [[NorseMythology Asgard]] (by triggering a late completion clause), Loki [[VoluntaryShapeshifting turned into]] [[GenderBender a mare]] in heat so the builder's horse would run off. He gave birth to Sleipnir, the eight-legged horse of Odin, who carries the honored dead to Valhalla. Loki's ''other'' animal children include the great wolf Fenrir and the Midgard Serpent, destined to kill Odin and Thor respectively.
* The Japanese seem to be most [[http://www.pitt.edu/~dash/japanlove.html fond]] of this trope, which could explain why this regularly appears all the time in their popular culture.
* It's quite common in East Asian culture in general for men in myths to end up marrying fox-spirits or ghosts. In one unusual case, a scholar in a Chinese folktale was visited in the night by the (human formed) spirit of a grasshopper, who he later saved from a spider.
* One Chief of the Macleod clan according to legend fell in love with a Fey. After twenty years she grew lonely for FairyLand. She left him with a half-fey child. Latter she heard the child crying and came back to lay a magic blanket on him. This magic blanket became the Fairy Flag could give the Macleods fey-help three times when called upon(as might be expected, this was in [[ProudWarriorRace Highlanders Favorite Sport]]). Photos of it were taken into battle by Macleods in WorldWarII. As the allies won maybe the [[FridgeLogic Wee Folk were doing their job right]].