Sibylle of Jülich-Cleves-Berg, Margravine of Burgau (26 August 1557 in Cleves – 1628 in Günzburg) was the daughter of Duke William the Rich[1] and his second wife, Archduchess Maria of Austria.

Born as the fifth daughter of William and Maria, her maternal grandparents were Ferdinand I, Holy Roman Emperor and Anne of Bohemia and Hungary.

Of Sibylle's mother and their relationship not much is known, apart from that she was generally considered a pious woman who may have grown mentally disturbed towards the end of her life because of religious scruples.

Their 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 Sibylle's, 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 Sibylle 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.

Edward Fortunatus, though of sufficient high birth, had little in fortune and had a reputation for living "an evil life",[3] though he was the nephew of the Lutheran John III, King of Sweden.

After he developed a mental illness, a power struggle broke out at court between Sibylle and her sister-in-law, Jakobea of Baden.

The marriage was childless but the couple raised Andrew (Sibylle's brother-in-law's) illegitimate children, Hans-Georg Degli Abizzi (b.