Sviatoslav Olgovich
Sviatoslav Olgovich (c. 1107–1164), son of Oleg of Chernigov, received Chernigov in 1154 after ruling lesser towns. Having helped his brother Vsevolod II seize Kiev in 1139, he was driven out after Vsevolod's death by Iziaslav II, who captured his brother Igor; a Kievan mob killed Igor in 1147.
Sviatoslav made common cause with Yuri Dolgorukiy; their meeting on the Moskva river in 1147 is Moscow's first appearance in the chronicles. He died on 14 February 1164, and his son Igor Sviatoslavich inspired The Tale of Igor's Campaign.