This list of mythical creatures that begin with this letter and I am constantly gathering information from each continent, and is continually being updated.
Oozlum Bird (Australian and British)
The oozlum bird, also spelled ouzelum, is a legendary creature found in Australian and British folk tales and legends. Some versions have it that, when startled, the bird will take off and fly around in ever-decreasing circles until it manages to fly up its own backside, disappearing completely, which adds to its rarity.
Other sources state that the bird flies backwards so that it can admire its own beautiful tail feathers, or because while it does not know where it is going, it likes to know where it has been. The Oxford English Dictionary describes it as "mythical bird displaying ridiculous behaviour" and speculates that the word could have been suggested by the word ouzel, meaning a blackbird.