This list of mythical creatures that begin with this letter and I am constantly gathering information from each continent, and is continually being updated.
Yara-ma-yha-who (Australian Aboriginal)
The Yara-ma-yha-who is a legendary creature found in Australian Aboriginal mythology. According to legend, the creature resembles a little red frog-like man with a very big head, a large mouth with no teeth and suckers on the ends of its hands and feet. The Yara-ma-yha-who is said to live in fig trees. Instead of hunting for food, it is described as waiting for an unsuspecting traveller to rest under the tree.
The creature then drops down and uses its suckers to drain the victim's blood. After that it swallows the person, drinks some water, and then takes a nap. When the Yara-ma-yha-who awakens, it regurgitates the victim, leaving them shorter than before. The victim's skin also has a reddish tint to it that it didn't have before. If this process is repeated, the victim becomes a Yara-ma-yha-who themselves.