This list of mythical creatures that begin with this letter and I am constantly gathering information from each continent, and is continually being updated.
Sea Monk (Medieval folklore)
The sea monk (also monk-fish or monkfish) was a sea creature found off the eastern coast of the Danish island of Zealand in 1546. It was described as a "fish" that outwardly resembled a human monk in his habit. A 2005 paper concluded that the animal was most likely an angelshark.
It has also been sighted by two fishermen and some nearby swimmers in Pula,Croatia in the year 2011 and is one of the more popular sightings of the cryptid in the Adriatic sea. It was described as a "fish" that looked superficially like a monk.