Olga (Saint Olga) (c.880-969) married the future
Igor[?], prince of
Kiev in
903. After his death, she ruled
Kievan Rus as regent (
945-c.
963) for their son,
Sviatoslav I. She spent great effort to avange her husbands death at the hands of the
Derevlians[?], and succeeded in slaughtering most of them. She was the first Rus ruler to convert to
Christianity, sometime between between 954 and 958. However, she failed to convert Sviatoslav, and it was left to his son and successor
Vladimir I to make
Christianity the lasting state religion.