|[[Image:|210px|alt=|'Duchess of Guelders']]|
|'Duchess of Guelders'|
|Reign||1 July 1538 - 23 November 1541|
|Coronation||31 July 1538|
|Predecessor||Charles II, Duke of Guelders|
|Successor||Isabella of Cleves|
|Spouse|| William, Duke of Julich-Cleves-Berg
|Issue|| Isabella, Queen of England|
|House|| House of Egmond (by birth)|
House of La Marck (by marriage)
|Father||Charles II, Duke of Guelders|
|Mother||Elisabeth of Brunswick - Luneberg|
|Born|| 27 September 1519 |
|Died|| 23 November 1541 (aged 22) |
Duchy of Cleves, Germany
|Burial||Parish church in Geldern|
Sophia, suo jure Duchess of Guelders (27 September 1519 - 23 November 1541) was the only child of Charles II, Duke of Guelders and Elisabeth of Brunswick-Lunberg and in 1537 married William of Julich-Cleves-Berg thus becoming Duchess Consort of the United Duchies.
Sophia of Guelders was born in Arnhem in the early hours of 27 September 1519. Her birth appears to have rendered her mother infertile as there were no further children from her parents' marriage. As heiress, she was well educated and grew up sympathizing with the ideals of the Protestant Reformation. By 1527, she professed Lutheranism and remarked, "When I am Duchess, there shall not be a single Catholic in my realm." However, as she became older she respected Catholics, but remained devout in her Lutheran faith. Her relationship with her mother became strained as she got older, however, she was obedient to her father. As heiress, she was an attractive prize in marriage and several proposals from the Hapsburgs between Sophia and Charles, later Holy Roman Emperor. Although Sophia showed interest, the proposal was rejected to keep Guelders from being absorbed by the Holy Roman Empire.
After the proposal from Archduke Charles was rejected, there was much need to find Sophia a suitable husband. Her mother favored a marriage between her daughter and the Dauphin of France, while her father proposed William, future Duke of Julich-Cleves-Berg. Duke William was chosen, as his territories bordered Guelders and he had his own claim to the Duchy. Aged 18, she married the Duke and became Duchess Consort. Within a month, it was apparent that the young bride was pregnant. On 16 April of the following year Sophia delivered a daughter, Isabella of Cleves. She had another pregnancy the following year, which ended in another daughter, Amalia. She and William enjoyed a loving marriage, despite it being arranged. William adored his daughters, although he wished for more children. In 1540, she became pregnant again, but she died before the child was born.
Soon after the birth of her daughter Isabella, her father died and Sophia became suo jure Duchess of Guelders, with her newborn daughter her heiress apparent. Eager to assure her people that she could rule, she traveled the duchy on horseback. She gave alms to the poor and prayed for many. She was sometimes referred to as "Sophia the Generous" for her tendency to donate to schools and churches. She inherited an impoverished state from wars with the Holy Roman Empire and raised taxes on the richer men. She managed to stabilize the economy and helped by buying products from many artisans.
In 1541, while pregnant with her fifth child, Duchess Sophia was riding horseback and suddenly her horse spooked and threw her from the saddle. Her husband rushed to her side and had her carried back to their palace where she was proclaimed dead from a broken neck, aged 22. Her duchy passed to her three year old daughter, who was sent to England to be raised by her paternal aunt, Anne of Cleves. Her husband retained control of the duchy and went to war once more with the Holy Roman Empire. Sophia was deeply mourned by her subjects and a extravagant funeral was arranged for her. Her husband married twice more after her death.