Y is for Yeti.
The Yeti is an ape-like creature of the Himalayas. In 1929. Lieutenant-Colonel Charles Howard-Bury coined the name Abominable Snowman, but Yeti is the preferred term. Abominable Snowman sounds like it has a bad attitude and a carrot for a nose. The Yeti is a cryptid, an animal which hasn't been documented by the scientific community. Every cryptid dreams of becoming a real, verifiable critter, losing that "cryp" in front of its name and becoming a tid like the rest of us.
Some animals have made it; the first preserved platypus displayed in Britain was damaged when scientists tried to cut off the duckbill, assuming it was a taxidermied fake. Giant Pandas were also once considered only legendary ditto for Narwhales.
The Yeti, on a scale of plausibility from 1 to 10, with 1 being jackalopes and 10 being coelacanths, stands at about 3, somewhere between the Loch Ness Monster and Sasquatch.
There world is a sadder and dimmer place as one by one we consign the might-be's to the status of mere folklore and earth's fauna is reduced to a very large but finite number of organisms, diminishing almost daily because of extinction. So even though no one seriously believes in the Yeti anymore, I hope he hangs in there for at least one more generation, the last of a short list of cryptids.