Olga is the East Slavic form of the Old Norse Helga ("holy, blessed"). Saint Olga of Kiev (c. 890-969) was the regent of Kievan Rus' (945-963) and the first Christian ruler of what would become Russia — baptized in Constantinople in 957, she set the stage for her grandson Vladimir's mass conversion of Rus' in 988. Famous in chronicle for her brutal revenge against the Drevlians who killed her husband Igor — she burned their capital using sparrows and pigeons carrying smoldering sulfur. One of the few female saints honored as "Equal-to-the-Apostles."
Subject of icons throughout Eastern Orthodox Christianity.
In Pythagorean numerology the letters of Olga reduce to 8, The Visionary. This is a traditional interpretive system, not a factual claim about the name.