Cosimo II de' Medici, Grand Duke of Tuscany (12 May 1590 – 28 February 1621) ruled as Grand Duke of Tuscany from 1609 to 1621.

He was the oldest son of Ferdinando I de' Medici, Grand Duke of Tuscany and Christine of Lorraine.

He married Maria Magdalena of Austria (October 7, 1589 – November 1, 1631), the daughter of Archduke Karl of Austria, on October 19, 1608. They had the following children:

• Maria Cristina (August 24, 1609 – August 9, 1632)
• Ferdinando (July 14, 1610 – May 23, 1670), who married Vittoria della Rovere (February 7, 1622 – March 6, 1694), the daughter of Francesco Ubaldo della Rovere, Prince of Urbino.
• Giancarlo (July 24, 1611 – January 23, 1663), made Cardinal in 1644.
• Margherita (May 31, 1612 – February 6, 1679), who married on October 11, 1628 to Odoardo I Farnese, Duke of Parma (1612-1646)
• Matteo (April 9, 1613 – October 14, 1617)
• Francesco (October 16, 1614 – July 25, 1634)
• Anna (July 21, 1616 – September 11, 1676) who married on June 10, 1646 to Ferdinand Karl, Archduke of Austria (1628-1672)
• Leopoldo (November 6, 1617 – November 10, 1675), made Cardinal in 1667.

He was succeeded by his oldest son, who reigned as Ferdinando II.