Slavic mythology · God of the underworld and cattle
Veles
Serpent, bear, willow and cattle: the underworld god who dwells in the waters beneath the roots of the world tree.
Stories and legends
Veles is the god of the earth, the waters, and the underworld, and also the guardian of herds, wealth, music, and magic. He sometimes turns into a great serpent, sometimes into a bear, a wolf, or a bearded old man, and the willow is his tree. Legend says that he lives beneath the waters at the roots of the world tree, decides where the dead go, and watches over the herds of shepherds and the harvest of the fields. Every winter he rises from underground, and in spring he battles Perun. He steals the herds and hides away the rain, Perun drives him back underground with lightning, the rain falls, and the earth comes back to life.
Origins of the story
What can be verified is scattered evidence for the name and functions. Veles, also called Volos, appears in ancient texts in connection with herds and wealth, and after Christianization some of his functions were taken up by the folk images of saints such as Saint Blaise. The battle story between Veles and Perun likewise has no complete record in ancient texts. It is a reconstruction theory put forward in the 20th century by the scholars Ivanov and Toporov, and Toporov himself, one of its proposers, later held reservations about it. Scholars still disagree on the theory, so it remains uncertain here. The image of Veles is a collection of many symbols, serpent, bear, wolf, willow, and more, so you should not reduce him simply to one animal god.
Places you can visit
You can sense the symbolism of Veles, low and damp places, among the willow groves by rivers and the pastures of Eastern Europe. Willows grow beside the water, and cattle and sheep graze along the riverbanks. At Slavic cultural festivals you can also see modern reconstructions of Veles idols, though those are modern works of restoration, not ancient originals. Around Žrnovnica in Croatia, legend speaks of a relief showing Perun defeating Veles, dated to around the 8th century, though that claim still leaves room for discussion.
Source leads: https://en.wikipedia.org/wiki/Veles_(god)；http://encyclopedia.thefreedictionary.com/Veles+(god)
Image source · Idol of Veles at a modern festival (Poland, 2019) · Wojsław Brożyna · CC BY-SA 4.0