Margaret Leijonhufvud or Margareta Eriksdotter was Queen of Sweden from 1536 to 1551 by marriage to King Gustav I. She played a political role as the advisor of, and the intermediary to, her spouse the King.

Gustav I, commonly known as Gustav Vasa, was King of Sweden from 1523 until his death in 1560, previously self-recognised Protector of the Realm (Riksföreståndare) from 1521, during the ongoing Swedish War of Liberation against King Christian II of Denmark, Norway and Sweden. Gustav rose to lead the Swedish War of Liberation following the Stockholm Bloodbath, where his father was executed. Gustav's election as king on 6 June 1523 and his triumphant entry into Stockholm eleven days later marked Sweden's final secession from the Kalmar Union.