The House of Olelkovich was a princely family from the Grand Duchy of Lithuania in the 15th and 16th centuries. Their main possession was the Duchy of Slutsk–Kapyl. They are sometimes known as Slutskys. They were descended from the Lithuanian Gediminids and Ruthenian Rurikids. According to the 1528 military census, the family was the fourth wealthiest magnate family in the Grand Duchy. However, its influence declined after the Union of Lublin (1569). The last member of the family was Sophia Olelkovich Radziwill (1585–1612), wife of Janusz Radziwiłł. She was elevated to sainthood in the Eastern Orthodox Church in 1983. As part of her marriage negotiations, she insisted on remaining a member of the Eastern Orthodox Church, despite her future husband's allegiance to Calvinism. She died in childbirth, as did the child. After her death, her considerable wealth and the Principality of Slutsk passed to the Radziwiłł family.

The House of Gediminid or simply the Gediminids were a dynasty of monarchs in the Grand Duchy of Lithuania that reigned from the 14th to the 16th century. A cadet branch of this family, known as the Jagiellonian dynasty, reigned also in the Kingdom of Poland, Kingdom of Hungary and Kingdom of Bohemia. Several other branches ranked among the leading aristocratic dynasties of Russia and Poland into recent times.