| Consort: | yes |
| Succession: | Electress consort of Saxony |
| Reign: | 16 August 1532 - 4 June 1547 |
| Spouse: | John Frederick I, Elector of Saxony |
| Issue: | John Frederick II, Duke of Saxony John William, Duke of Saxe-Weimar John Frederick III, Duke of Saxony |
| Issue-Link: |
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| Issue-Pipe: | Among others |
| House: | La Marck |
| Father: | John III, Duke of Cleves |
| Mother: | Maria of Jülich-Berg |
| Birth Date: | 17 January 1512 |
| Birth Place: | Düsseldorf |
| Death Place: | Weimar |
| Burial Place: | St. Peter und Paul, Weimar |
Sibylle of Cleves (17 January 1512 - 21 February 1554) was electress consort of Saxony.
Born in Düsseldorf,[1] she was the eldest daughter of John III of the House of La Marck, Duke of Jülich jure uxoris, Cleves, Berg jure uxoris, Count of Mark, also known as de la Marck and Ravensberg jure uxoris (often referred to as Duke of Cleves) who died in 1538, and his wife Maria, Duchess of Julich-Berg (1491–1543). Her younger siblings were two sisters, Anne (later Queen of England) and Amalia, and a brother, William, who became Duke of Jülich-Cleves-Berg.
In September 1526, Sibylle was betrothed to Electoral Prince John Frederick of Saxony in the Schloss Burg an der Wupper. After lengthy negotiations about the dowry, the lavish wedding ceremony, preceded by an elaborate procession, took place in Torgau on 9 February 1527. They had four sons.
After the death of his father in 1532, Johann Friedrich became the elector of Saxony and Sibylle the electress.
The correspondence between Sibylle and her husband during his captivity as a consequence of the Schmalkaldic War, showed a devoted and intimate couple. In the meanwhile, during the siege of Wittenberg, the electress protected the city in her husband's absence. To save his wife and sons, and to prevent Wittenberg from being destroyed, John Frederick conceded the Capitulation of Wittenberg and resigned the government of his country in favor of Maurice of Saxony.
In 1552, after five years of captivity, the deposed elector was finally reunited with his family. However, the reunion was short-lived: in 1554 both Sibylle and Johan Frederick I died within a month of each other. They were buried in the City Church of Weimar.
Like her husband, Sibylle was a staunch supporter of the Reformation. The Thuringian reformer Justus Menius dedicated to her the mirrors for princes writing Oeconomia Christiana.