This list of mythical creatures that begin with this letter and I am constantly gathering information from each continent, and is continually being updated.
Ushi-oni (Japanese)
Ushi-oni have brutal, savage personalites. Their appearance varies, mainly based on geographical location. They usually have an ox's head with sharp upward-curving horns, wicked fangs and a slender tongue. They spit poison and enjoy killing and eating humans. Their body is most commonly depicted as spider-like with six legs and long singular claws at the end of each appendage.
In other descriptions, they have the head of an ox and an oni's torso. Certain legends claim that they appear in front of temple gates in the mountains wearing human clothing, or flying with the wings of an insect. Other ushi-oni have a reverse appearance, with an oni's head and an ox's body.