Agatha (before 1030 – after 1070) was married to Edward the Exile, a candidate for the throne of England, and mother of Edgar Ætheling, Saint Margaret of Scotland and Cristina.
The earliest-surviving source, the Anglo-Saxon Chronicle, along with John of Worcester's Chronicon ex chronicis and its associated genealogical tables (sometimes named separately as Regalis prosapia Anglorum), Symeon of Durham (thaes ceseres maga) and Ailred of Rievaulx describe Agatha as a kinswoman of "Emperor Henry", the latter explicitly making her daughter of his brother (filia germani imperatoris Henrici).
Geoffrey Gaimar in Lestoire des Engles states that she was daughter of the Hungarian king and queen (Li reis sa fille), although he places the marriage at a time when Edward is thought still to have been in Kiev, while Orderic Vitalis in Historiae Ecclesiasticae is more specific, naming her father as king Solomon (filiam Salomonis Regis Hunorum), even though he was actually a contemporary of Agatha's children.
Suhm (1777, Geschichte Dänmarks, Norwegen und Holsteins) and Istvan Katona (1779, Historia Critica Regum Hungariae) each suggested that Agatha was the daughter of Henry II's brother Bruno of Augsburg (an ecclesiastic described as beatae memoriae, with no known issue), while Daniel Cornides (1778, Regum Hungariae) tried to harmonise the German and Hungarian claims, making Agatha daughter of Henry II's sister Giselle of Bavaria, wife of Stephen I of Hungary.
Likewise, all of the solutions involving Henry II would seem to make Agatha much older than her husband, and prohibitively old at the time of the birth of her last child, Edgar.
Based on a more strict translation of the Latin description used by John of Worcester and others as well as the supposition that Henry III was the Emperor designated in the Anglo-Saxon Chronicle, genealogist Szabolcs de Vajay popularised another idea first suggested in 1939.
[8] De Vajay reevaluated the chronology of the marriages and children of Gisela and concluded that Agatha was the daughter of Henry III's elder (uterine) half-brother, Liudolf, Margrave of Frisia.
[9] This theory saw broad acceptance for several decades[10] until René Jetté resurrected a Kievan solution to the problem,[11] since which time opinion has been divided among several competing possibilities.
[12] Jetté pointed out that William of Malmesbury in De Gestis Regis Anglorum and several later chronicles unambiguously state that Agatha's sister was a Queen of Hungary.
[15] This Felch/Jetté theory accords with the seemingly incongruous statements of Geoffrey Gaimar and Roger of Howden that, while living in Kiev, Edward took a native-born wife "of noble parentage" or that his father-in-law was a "Rus king".
[16] Eduard Hlawitschka also identifies Agatha as a daughter of Yaroslav, pointing out that Adam of Bremen,[17] who was well informed on North-European affairs, noted around 1074 that Edward was exiled in Kievan Rus (E[d]mund, vir bellicosus, in gratiam victoris sublatus est; filii eius in Ruzziam exilio dampnati)[17] and that the author of Leges Edwardi confessoris, who had strong ties with Agatha's children, Queen Margaret of Scotland and her sister Cristina, and could thus reasonably be expected to be aware of their descent, recorded around 1120 that Edward went to the land of the Rus and that there he married a noblewoman.
He would later point out the occurrence of the name Maria in the next generation of the Kievan dynasty, and suggested that Agatha could instead have been sister of the Byzantine wife of Vsevolod I of Kiev, that the tradition of imperial connections had confused which Empire was involved.
However, he subsequently studied the sources and particularly the chronology of this dynasty in more detail and concluded that this solution was unlikely, though he did favor a reconstruction making Yaroslav the son, rather than the step-son, of the Byzantine princess Anna Porphyrogeneta.
Count Cristinus married a Saxon noblewoman, Oda of Haldensleben, who is hypothesized to have been maternally a granddaughter of Vladimir I of Kiev by a German kinswoman of Emperor Henry III.
John P. Ravilious has proposed that Agatha was daughter of Mieszko II Lambert of Poland by his German wife, making her kinswoman of both Emperors Henry, as well as sister of a Hungarian queen, who was married to Béla I.
This argument is further supported by the replacement by Andrew I of Hungary (husband of Anastasia of Kiev) of his brother Béla as his heir apparent with his young son Salomon in 1057.