This list of mythical creatures that begin with this letter and I am constantly gathering information from each continent, and is continually being updated.
Mokele-mbembe (Congo)
The mokele-mbembe, Lingala for "one who stops the flow of rivers", is a mythical water-dwelling entity that supposedly lives in the Congo River Basin, sometimes described as a living creature, sometimes as a spirit. Descriptions vary widely among those who claim to have seen the creature, but it is often described as a large quadrupedal herbivore with smooth skin, a long neck and a single tooth or horn.
Most mainstream experts believe that mokele-mbembe, as reported by Congolese natives, was probably inspired by the black rhinoceros, which once thrived in the region. Historian Edward Guimont has argued that the mokele-mbembe myth grows out of earlier pseudohistorical claims about Great Zimbabwe, and in turn influenced the later reptilian conspiracy theory.