Date of birth unknown; died in 1224. Russian prince.
At the beginning of the 13th century, Viachko was the prince of the Koknes fortress on the Zapadnaia Dvina River. He fought actively against the aggression of the German knights. When he did not receive aid from Polotsk in 1207, he burned his castle and went to Rus’. In 1223 the rulers of Novgorod and Prince lurii Vsevolodovich of Vladimir-Suzdal’ sent Viachko with a detachment of Russian troops to lurev’ (Tartu) to help the Estonians, who were struggling against the aggression of the German knights. Viachko, refusing to surrender into captivity, perished in the city during the German siege.