Oleg Svyatoslavich of Chernigiv (Ukrainian: Олег Святославич), sometimes also styled as of Tmutarakan, was a Rurikid prince whose equivocal adventures ignited political unrest in Kievan Rus' at the turn of the 11th and 12th centuries.
One of the sons of Sviatoslav II of Kiev, Oleg was named after his grand uncle. In the 1070s, he ruled the towns of Rostov and Lutsk, whence he made a raid into Bohemia in 1076. The same year his father died in Kiev and was succeeded by his brother Vsevolod. Failing to get along with him, Oleg had to flee to a distant Chernihivian domain on the Black Sea shore, called Tmutarakan. There, in 1078, he made an alliance with the Kipchaks, and with their support returned to his father's patrimony, Chernihiv (Ukraine). It was the first time when Slavic princes, in order to achieve their ends, brought pagan hordes to the walls of Russian cities.
On October 3, 1078 Oleg's forces clashed with Vsevolod of Kiev at the Nezhatinnaya Niva (or Nezhatina Niva, today's Nizhyn). He was defeated and escaped to Tmutarakan, where the Khazars had him imprisoned and sent in chains to Constantinople. The emperor, who was a relative and ally of Vsevolod, exiled him to Rhodes. There he married a noble lady, Theophano Mouzalonissa, who bore him several children.
Four years later, we again find him active in Tmutarakan, where he adopted the title "archon of Khazaria". In 1094, he returned with the Kipchaks to Rus' and captured Chernihiv. There ensued a prolonged internecine struggle with his cousins Sviatopolk and Vladimir Monomakh. One of the most prominent princes of Kievan period who never attained the Kievan throne, he died on August 1, 1115 and was buried in Chernihiv.
The Tale of Igor's Campaign styles him Gorislavich, poetically deriving his patronymic from the Russian word for sorrow. His descendants, known as Olgovichi, were archrivals of Vladimir's descendants (known as Monomakhovichi) in their struggle for supremacy in Rus'.
His son was Igor II of Kiev.