Mahishasur
The bull-man demon, he drove Indra and other gods out of heaven, and was unbeatable by men; which necessitated the creation of Durga/Devi with the combined powers of all Gods so that he can be destroyed.He had a boon that he could be killed only by a woman and so Durga had to come forward to kill him.Navratre’s are celebrated in India to demonstrate Durga’s triumph over the evil demon.