Adi (mythology)
In Hindu mythology Adi is an asura killed by Shiva for taking the disguise of Shiva's consort Parvati.
Story
Adi was a powerful demon like his father Andhaka. He decided to avenge his father's death by killing Shiva. But he knew that Shiva was powerful and invincible. Adi did tapasya to please Brahma. When Brahma appeared before him, he was unable to express his desire clearly. Brahma took advantage of the ambiguity of the words and granted him the boon, but with the twist that made him invincible only when he was in the form of a demon, not in any disguise. Adi was aware of this limitation. He thought he was ready to face Shiva and kill him. Armed with the power he got from Brahma, he went to Mount Kailasha, the abode of Shiva, in the guise of a snake, because snakes were allowed to enter Kailash freely. But when he tried to enter into the presence of Shiva in the guise of Parvati, Shiva recognized him and killed him instantly.
Another Version
Another version of the story tells us that Brahma granted him another boon that he can learn warfare under Shiva. Adi started to train under Shiva. However after a few years he started to trouble the residents of Mount Kailasha. Adi appeared as Parvati in front of Shiva and asked him for one more chance. However Shiva realised this was Adi and killed him with his trishula. Adi begged for forgiveness and Shiva gave him moksha.