Of course, no one has ever seen a mythological or fantastic creature. No one has ever seen a dragon, a centaur or unicorn. But that doesn't stop people from believing they had seen them, does it? And here, I'm not talking if travelers claimed they had seen one, but if there are any records of people actually believing that they had witnessed a monster.

Perhaps being in a thunderstorm, a lightning would reveal a cloud that looked like a dragon? Or from far away a passing party of riders might look like centaurs or something.

I ask this also because sometimes it seems strange to me that people would have believed in all of these fantastic tales without ever having seen anything like it.

Thanks!