Shiva (also spelt Siva, has many names) is a Hindu god. He is the third god of the Trimurti (popularly called the "Hindu trinity"). In the trimurti, Shiva is the destroyer, while Brahma and Vishnu are creator and preserver, respectively. However, even though he represents destruction, he is viewed as a positive force (The Destroyer of Evil), since creation follows on from destruction. Some Hindus believe in a legend that he came from an egg laid by Ammavaru while others say he is anadi (without beginning/birth) and ananth (without end/death). Shivas worshippers are called Shaivaites.
Some of his chief attributes are signified by his hundreds of names, such as Mahabaleshwar (Great God of Strength), Tryambakam (Three-Eyed One, i.e. All-Knowing), Mahakala (Great Time, i.e. Conqueror of Time), etc.
Shiva is the chief god of Shaivism, one of the two main branches of Hinduism today (the other being Vaishnavism). His abode is called Kailasa. His holy mount (called vahana in Sanskrit) is Nandi, the Bull. His attendant is named Bhadra. He is usually represented by a phallus, the Shiva linga (or lingam).
Shiva's consort is Devi, a goddess who comes in many different forms, one of whom is Kali, the goddess of death. Parvati, a more pacific form of Devi is also popular. Shiva also married Sati, daughter of Daksha, who forbade the marriage. Sati disobeyed her father and Daksha held a sacrifice to Vishnu, but did not invite Shiva. In disgust, Sati sacrificed herself in the same fire Daksha used in his sacrifice. Shiva crashed the party, angry at the death of his wife, and killed many of the guests, as well as decapitating Daksha, though he later replaced his head with that of a goat. Shiva created the monster Virabhadra during his quarrel with Daksha.
Shiva and Parvati are the parents of Karttikeya and Ganesha, the elephant-headed god of wisdom. He acquired his head due to the actions of Shiva, who decapitated him because Ganesha refused to allow him to enter the bath while Parvati was bathing. Shiva had to give him the new head to placate his wife. In another version, Parvati showed the child off to Shiva, whose face burned his head to ashes, which Brahma told Shiva to replace with the first head he could find, an elephant.
According to the foundational myth of Kalism, Kali came into existence when Shiva looked into himself; she is his mirror image. Kali is often depicted standing on top of Shiva's dead and lifeless body. Shiva is shown dead to signify his passiveness in relation to Kali.
Another version: She had gone out to kill demons but drunk with blood lust, she went on a rampage. To stop her, Shiva went and lay down on the ground in front of her path. When she stepped on him, she looked down and realized that she had just stepped on Shiva. Feeling ashamed, she stuck out her tongue, and the rampage ended.
Some Hindus believe Shiva to be just one of many different forms of the universal Atman, or Brahman, a monistic entity to which all things, Shiva and everything else, are identical. Others see him as the one true God from whom all the other deities and principles are emanations, essentially a monotheistic understanding usually related to the bhakti sects of Shaivism.
Traditionally, unlike Vishnu, Shiva does not have any avatars. However, several persons have been claimed as avatars of him, such as Shankara. Some people consider Hanuman to be an avatar of Shiva.
Nayanars (or Nayanmars), saints from Southern India, were mostly responsible for development of Shiva sect in the Middle Ages.
The important Shaivite sects were Kashmir Shavaites from Northern India, Lingayats and Virasaivas from Southern India. Saiva Siddhanta is a major Shaivite theory developed in Southern India.
This is not complete yet. More details on Shaivite texts/schools needed.
