I know most of you have heard this before, but I'm curious. What is your thought that some of the mythological and fantasy creatures were/are animals from other planets. Your thoughts that perhaps some of those creature were genetic experimentations. Possible or not? I think perhaps possible on both accounts....it's interesting anyway.

Anything is possible. I have always wondered if Aliens visited this planet when dinosaurs were walking the earth if maybe they didn't take some to put on other planets. There might be some alien zoo out there somewhere with dinosaurs walking around. Or maybe I just have too much time on my hands to think about this stuff.

Most of the mythical creature in fables seem to be created/imagined through known animals or mixtures of different animals on Earth. With this being the case, I would suspect an 'alien' mythical creature would be something completely different in appearence from that which we know.

Certain creatures are far too widely believed I think, to be alien in origin... Look at unicorns and dragons, especially. Believed by almost every culture, I would think it would take a lot of time for them to spread everywhere...still not out of the realm of possibility, but unlikely I'd say...

You would be thinking of Elves, Fairies, Centaurs, Bigfoot, and so forth? If life exists elsewhere it is possible that these beings were in ages past otherworldly. In fact, they may be Ambassador-Observers reporting to some authority.
It is also possible that they are exclusive to this planet. Who is to say that they were not created--with or without the evolutionary process?
Perhaps some are demonic and some Angelic.
That some did and maybe still do exist is almost undeniable, as the legends are too widespread and ancient to be of recent origin.
For example, I tend to believe that only one creature historically fits the description of a Unicorn--four legs, a single horn in the facial area, the Rhinocerous. It is not a pretty horse or goat, but it exists. Little people, leprechauns, Elves, and fairies etc. could be a race of humans subject to a type of super-dwarfism.
By the way, that Bible UFO connection site you gave looks interesting. I had to save it for future perusal.
I freely admit that I have no answer. I also admit that I have been told that I have strange ideas for a Christian. So Be It! I think God gave me a brain to be used, not wasted by disuse. I sincerely hope I am not out of line. That last part is not really related to the question, is it?