Cernunnos is a Celtic god associated with sexuality, fertility, the hunt, and the underworld. He was worshipped by the iron age Celts all across Europe as late as the first century CE, and his worship must have begun centuries before that.
Cernunnos is nearly always portrayed with animals, in particular the stag. Less often he is associated with other beasts, including bulls, dogs and rats. He is also frequently associated with a unique beast that seems to belong only to him: a serpent with the horns of a ram. The serpent was commonly associated with death and the otherworld, and is hence described as cthonic. Cernunnos carries it in his left hand, and in his right he carries a torc, the Celtic symbol of nobility, the symbol of having been initiated into that special state.