Executions of Cossacks in Lebedin (Ukrainian: Катівня в Лебедині), (Russian: Казни казаков в Лебедине) in 1708–1709 was a large-scale execution of Ukrainian Cossacks suspected of having sided with Hetman Ivan Mazepa after his break with Tsar Peter I during the Great Northern War. Cossack officials summoned to the Council of Hlukhiv who did not report to it were arrested, tortured and executed for treason. The exact number of victims is not known, but the minutes of the historical accounts indicate at least 900.