Duchess Magdalene of Jülich-Cleves-Berg (2 November 1553 – 30 August 1633) was the fifth child of Duke William "the Rich" of Jülich-Cleves-Berg and Maria of Austria, a daughter of Emperor Ferdinand I. Magdalenes paternal aunt Amalia played a great part in raising her nieces though William resented the fact that she was a Lutheran and tried to influence his daughters to abandon the Catholic faith.

Another aunt of Sibylles; Anne was for a short time the wife of the Protestant king Henry VIII of England.

The influence of Lutheran sentiment at the Düsseldorf court worried the papal ambassadors present and they suggested that Magdalene and her sisters be either sent to their aunt Anna of Austria in Munich or that they be sent to a convent where they would receive proper guidance in the Catholic faith.

Since all claimants were members of comprehensive European coalitions and so the Habsburgs and France were indirectly involved, an international conflict threatened: the War of the Jülich succession.

In the meantime, Magdalena's husband had died in 1604 and his claim had been inherited by her eldest son John II (1584–1635), who did not receive a share under the Treaty of Xanten.