Caterina de' Medici (2 May 1593 – 17 April 1629) was a Tuscan noblewoman of the Medici family. She became Duchess of Mantua and Montferrat as the second wife of Duke Ferdinando and Governor of Siena from 1627. She was the second daughter of Grand Duke Ferdinando I of Tuscany and his wife Christina of Lorraine.

The second daughter and third child of Grand Duke Ferdinando I and his wife, Christina of Lorraine, Caterina, named after the eponymous Queen of France (who was also her great-grandmother) was born in Florence on 2 May 1593.

Caterina was considered as a potential spouse to Henry Frederick, Prince of Wales, heir to the three Kingdoms of England, Scotland and Ireland, but his Anglican religion presented an insurmountable barrier.

Eventually, she married in 1617 Ferdinando Gonzaga, Duke of Mantua and Montferrat; the marriage, however, was childless.

Upon being made a widow in 1626, she returned to Tuscany. Her nephew, Grand Duke Ferdinando II, created her Governess of Siena in 1627, where she died of smallpox two years later.

In later life, Caterina garnered a reputation for intense piety. Historian Colonel G.F. Young asserts that she bore a striking resemblance to her brother Cosimo II and sister Claudia. She was interred in the Medicean necropolis, the Basilica of San Lorenzo.

• Parrott, David (1997). "The Mantuan Succession, 1627–31: A Sovereignty Dispute in Early Modern Europe". The English Historical Review. CXII, Issue 445, February (445). Oxford Academic: 20–65. doi:10.1093/ehr/CXII.445.20.
• Young, G.F.: The Medici: Volume II, John Murray, London, 1920

Caterina de' Medici, Governor of Siena House of Medici Born: 2 May 1593 Died: 17 April 1629
Italian royalty
Preceded by Margaret of Savoy	Duchess of Mantua 1617–1626	Succeeded by Isabella Gonzaga
	Duchess of Montferrat 1617–1626
Political offices
Preceded by Fabrizio Colloredo	Governor of Siena 1627–1629	Succeeded by Mattias de' Medici