Charles IX, also Carl (; 4 October 1550 – 30 October 1611), was King of Sweden from 1604 until his death. He was the youngest son of King Gustav I and his second wife, Margaret Leijonhufvud, brother of Eric XIV and John III, and uncle of Sigismund who was king of both Sweden and Poland. By his father's will he got, by way of appanage, the Duchy of Södermanland, which included the provinces of Närke and Värmland; but he did not come into actual possession of them till after the fall of Eric and the succession to the throne of John in 1568.