東西教會大分裂
Hilarion or Ilarion (, , ) was the first non-Greek Metropolitan of Kiev and all Rus in Medieval Kievan Rus (Ruthenia). He held the metropolitan post before or during the ongoing 11th century East–West Schism. While there is not much verifiable information regarding Hilarion's biography, there are several aspects of his life which have come to be generally accepted.