Introduction
Virabhadra, "auspicious hero", is a fierce manifestation created by Shiva from a lock of his own hair, born of his grief and rage at the death of Sati, and best known for destroying the sacrifice of her father Daksha.
This article follows the Puranic tradition. Where a detail differs between texts, the article says so.
Creation
On learning of Sati's death, Shiva, in his fury, tore a lock of matted hair from his head and dashed it to the ground; from it arose Virabhadra, a being of terrifying appearance, along with, in some accounts, the fierce goddess Bhadrakali created alongside him.
Destroying the sacrifice
Shiva sent Virabhadra, with a host of Ganas, to Daksha's sacrifice. Virabhadra destroyed the ritual grounds, scattered or injured the assembled gods, and beheaded Daksha himself. When Shiva later relented at the gods' pleading, Daksha was restored to life with the head of a goat, and the sacrifice was allowed to be completed properly, with due honour paid to Shiva.
Worship
Virabhadra is worshipped as a fierce protective deity in several regions of South India, notably in Karnataka and Andhra Pradesh, often at shrines associated with the wider Shaiva tradition of Daksha's sacrifice.