Oleg Svyatoslavich (Russian: Олег Святославич; c. 1052 – 1 August 1115) was a prince from Kievan Rus' whose equivocal adventures ignited political unrest in the country at the turn of the 11th and 12th centuries.

[4] The Tale of Igor's Campaign styles him Gorislavich, poetically deriving his patronymic from the Russian word for sorrow.

[11] The two cousins together commanded the troops Oleg's father sent to assist Boleslav II of Poland in Bohemia in 1076, according to the Russian Primary Chronicle.

[14] The new grand prince seems to have confirmed Oleg's rule in Vladimir, because no source makes mention of a conflict between them.

[19][20] Together with his cousin, Boris Vyacheslavich, who had also settled in Tmutarakan, Oleg made an alliance with the Cumans and invaded Rus' in the summer of 1078.

[22] The Russian Primary Chronicle accuses Oleg and Boris of being the first to lead "the pagans to attack the land of Rus'".

[23][24] However, Vladimir Monomach, in his Instruction, reveals that he and his father, Vsevolod had hired Cumans when attacking Polotsk in the previous year.

[29] The three warring factions were related dynastic princely branches, each descended from three sons of Yaroslav the Wise, and each of whom had reigned as grand prince of Kiev:[29] While he was still alive, Vsevolod had appointed his son Vladimir Monomakh as governor over Chernigov, while the Sviatoslavichi probably still controlled the eastern half of Chernigov centred around Murom (split off as the Principality of Murom decades later).

[29] Although Oleg's father Sviatoslav II had reigned as grand prince of Kiev from 1073 until his death in 1076, he had seized power out of order by driving out is brother Iziaslav I.

[29] While Monomakh resettled in Pereyaslavl, his sons still controlled eastern Chernigovia, including Murom on the river Oka, resisting Oleg.