Veles (aka Volos). The old Slavic god of cattle, wealth, and trade. He was one of the chief deities in the pantheon of pagan Rus’. In concluding treaties with the Byzantines (see Byzantine Empire) the Kyivan princes swore an oath to Perun and Veles. With the adoption of Christianity Saint Vlas (Vlasii) replaced Veles as the protector of livestock.
Encyclopedia of Ukraine