Some mythical creatures have their origin in traditional mythology and have been believed to be real creatures, for example the dragon, the unicorn, and griffin. Others were based on real encounters, originating in garbled accounts of travelers' tales, such as the Vegetable Lamb of Tartary, which supposedly grew tethered to the earth (and was actually a type of fern).
Conversely, some creatures downplayed as just storytelling, have been rediscovered and found to be real in recent times, such as the Giant Squid (the Kraken). In Africa, Natives of the Congo told European visitors of an animal that looked like a cross between a zebra and a giraffe. While the visitors assumed the stories were just folk tales, in 1901, Sir Harry Johnstonbrought back pelts that proved the creature, which we now call the okapi, was real.
Nessie (Loch Ness Monster)
Scape Ore Monster
Gef The Talking Mongoose