Ann VanderMeer has created this comprehensive analysis regarding which mythical beasts would and would not be kosher. This list could really come in handy under the right circumstances. Now, for bonus points, calculate the intersection of this list with a notional list of halal imaginary beasts.
Dragon – A: "No reptiles or amphibians." EM: "No exceptions? What about if it chews its cud?" A: "Shut up."
Encantado (dolphin-human shapeshifter) – EM: "Surely it's kosher when it's a dolphin." A: "A dolphin is a mammal just like you. It has no scales, even though it has fins. Besides, what if it starts changing while you're eating it?"
ET – A: "…..?" EM: "It had cloven hooves." A: "It's a humanoid." EM: "It looked like a pile of dung. It seemed to chew cud. Would any alien be automatically un-kosher?" A: "I guess it really depends on the alien–like a plant?" EM: "An alien that comes down to Earth." A: "No, because they wouldn't be considered an animal." EM: "What if they looked just like a cow, but with a brain?" A: "Cows have brains." EM: "Arggh!" A: "But cows don't travel to other planets using their brains." EM: "My point exactly!" A: "Anything intelligent is not kosher."
Headless Mule (fire-spewing, headless, spectral mule) – A: "No, because the mule itself, even if it weren't fire-breathing, isn't kosher. The fire doesn't cleanse it." EM: "But it's self-cooking!"
Hippocamp (horse-fish) – A: "Unfortunately, the horse part makes it treyf, and a little bit of treyf makes everything treyf. So if you had 99 percent fish and one percent horse it would still be treyf." EM: "And a really fucked up looking hippocamp!"
(via Making Light)