Nope, it's not even kind of real. They are based on real mythological creatures (the chimera you're thinking of that Perseus slew, and griffins were considered guardians of the gods), but I played with the imagery and used, at least for the chimera in my head, imagery that was more from Dante's Divine Comedy than Greek myth (because that more closely matched the monster Angeal became in the big boss fight--the chimera in the Divine Comedy was more like a manticore than a chimera, because it had a human face), and then proceeded to Make Shit Up. XD
And yeah, now that you mention it, it is sort of like Frankenstein's monster, isn't it?