This list of mythical creatures that begin with this letter and I am constantly gathering information from each continent, and is continually being updated.
Jinn (Arabian, Islamic)
Although generally invisible, jinn are supposed to be composed of thin and subtle bodies, and can change at will. They favour a snake form, but can also choose to appear as scorpions, lizards, or as humans. They may even engage in sexual affairs with humans and produce offspring. If they are injured by someone, they usually seek revenge or possess the assailant's body, refusing to leave it until forced to do so by exorcism.
In common folklore, jinn are capable of assuming human or animal form and are said to dwell in all conceivable inanimate objects such as trees, ruins, and underneath the earth, in the air, and in fire. They possess the bodily needs of human beings and can even be killed, but they are free from all physical restraints.