I don't believe in vampires, per se, but I think there might well be vampire-like spirits that suck energy from you and try to distract you from spiritual growth -- demons.
If you include mythical creatures like satyrs, centaurs and the like, I think some of them may have been primitive misunderstanding of humans dressed in strange clothing or riding horses.
For instance, horse riding became common about 4000 BC in the area of modern Ukraine. But primitive people who had never seen a person on horseback may have thought they were seeing half-man, half-horse when they first saw a rider. So, this may be how the myth of Centaurs may have started. In fact, the centaur Chiron, teacher of many in Greek mythology, may have merely been a cavalryman of a more advanced people -- perhaps part of the children of Atlantis. The Atlanteans, according to Plato, were supposed to to have had a great cavalry as well as a great navy. Poseidon, possibly the symbol for early patriarchal Atlantis was said to be god of horses, earthquakes and the sea.
The dragons of worldwide myths may have been mechanical aircraft, rather than flesh-and-blood creatures. If you look carefully at the details of many of the dragon myths, like that of the Egyptian merchant-prince, Cadmus and the dragon, Jason and Medea, and Cecrops, these could all have been explained by a golden-colored aircraft (possibly anti-gravity) that happened to be shaped like a snake (drakon in Greek). In fact, the golden dragon that protected the Golden Fleece in ancient Colchis (modern Georgia) may well be the same golden dragon on which Medea fled Athens when her 2nd husband banished her.
I suspect, after Medea had experienced so much disappointment with men in her life (in Colchis, with a cheating Jason, and the unsympathetic king of Athens), that she may have started her own tribe of women. And what better name to give such a tribe than "Mother Atlantis" (ama-Atlan -- Amazon)?