Charles IV (5 April 1604, Nancy – 18 September 1675, Allenbach) was Duke of Lorraine from 1624 until his death in 1675, with a brief interruption in 1634, when he abdicated under French pressure in favor of his younger brother, Nicholas Francis.

He came to lose his duchy because of his notionally anti-French policy for in 1633, French troops invaded Lorraine in retaliation for Charles's support of Gaston d'Orléans—who repeatedly plotted against Richelieu's governance of France under the childless Louis XIII and treated dangerously with its enemies as a young heir presumptive—and Richelieu's policies were always anti-Habsburg so as to increase the strength and prestige of France at the expense of the two dynasties. Gaston d'Orléans, frequently sided with either branch of the Habsburg family against Richelieu, who was de facto ruler of France as its Chief Minister, and had to flee several times to avoid charges and trial for treason. His allies and confederates generally bore the price of these escapades by the young and impetuous heir and Charles IV was one such. On one visit to the ducal court at Nancy, the widowed Gaston fell in love with Charles's 15-year-old sister and married her secretly, which so infuriated the king that he convened the clergy of France and the Parlement of Paris to void the marriage, giving consent only on his death bed.

In that circumstance and sense, Charles was a casualty of the fierce factional infighting in the French court between the King's brother Gaston d'Orléans, and Cardinal Richelieu, even though technically, Lorraine was subject to the Holy Roman Empire and the Emperor Ferdinand II of Austria. Forced to make humiliating concessions to France, he abdicated under the French pressure and invasion in 1634 in favor of his brother, Nicholas Francis, and entered the imperial service in the Thirty Years' War. Shortly thereafter, Nicholas Francis too fled into exile and abdicated his claims, which were now taken up once again by Charles, who remained Duke of Lorraine in exile for the next quarter century.

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