Margaret of Sicily (1237–1270), (Margarethe von Hohenstaufen), Imperial Princess and Margravine of Meissen, was the eldest -according to some sources [1] she was born in 1241 and, in consequence, was the youngest and not the oldest- legitimate daughter of Frederick II, Holy Roman Emperor, King of Sicily, by his third wife, Isabella of England. 

Frederick I, called the Brave or the Bitten (German Friedrich der Freidige or Friedrich der Gebissene; 1257, Eisenach – 16 November 1323, Eisenach) was margrave of Meissen and landgrave of Thuringia. He was the son of Albert II, Margrave of Meissen, and Margaret of Sicily.

Paralyzed by a stroke since 1321, Frederick died on 16 November 1323. His bones were later moved from Eisenach to Grimmenstein Castle in Gotha and after its demolition were buried in Friedenstein Castle; however, his tomb was erected in Reinhardsbrunn. In 1285, he married Agnes, the daughter of Count Meinhard II of Gorizia-Tyrol and Elisabeth of Bavaria, widowed mother of Conradin, and after her death he married Elizabeth of Arnshaugk, the daughter of his stepmother, in 1303. Only two children survived him, Elizabeth, who was married to Henry II, Landgrave of Hesse, in 1322, and Frederick, his successor.