Parad Nandi 

Nandi is the vahana (vehicle) of Shiva. As an independent deity, the bull was in ancient times, the Lord of Joy (Nandikeshvara), and was represented as a man with a bull’s head. Joy, i.e., music and dance, were seen as the fundamental forces of creation, an aspect which was later transferred to Shiva. Later it was said of Nandikeshvara that he was a rishi (wise man) who guarded Shiva’s door to become divine in this way.