Bhairavamurti is considered as Lord Shiva in some ethics and considered as the power of Lord Shiva in others. However, the word Bhairava means the Anger form of Lord Shiva or the ultimate power of Lord Shiva. The Bhairavamurthi is considered as the most ferocious Gods in Hinduism, according to the Beliefs of Shaivism.
The existence of Bhairava is depicted in a situation where Lord Vishnu was in conversation with Lord Brahma about the Supreme Power in the Universe. When Lord Vishnu asked Brahma, that who is the Supreme power of the Universe, with his at most arrogance, Lord Brahma replied with his fifth head that he himself is the only Supreme power of the Universe as he creates all the beings on the Earth.
Lord Vishnu got convinced with what Brahma has said and he was about to accept that. Just then Lord Shiva appeared in front of them and replied in anger that he is the cause for all the creation and they two have evolved from him. As Lord Brahma had lied with his fifth head, Bhairava had cut off that head and as Vishnu had accepted the fact, Bhairava had take out his blood. For this reason, the deity of Bhairava holds the skull in one hand and the tumbler of Blood holding in the other hand.
This most ferocious form of Lord Shiva is being worshipped across the world and is revered by most of Shaivites. The Temples of Bhairava in India are also known as Kalabhairava Temples.