Henry IV the Pious, Duke of Saxony (German: Heinrich der Fromme) (Dresden, 16 March 1473 – Dresden, 18 August 1541) was a Duke of Saxony from the House of Wettin.

Heinrich was the second son of Albert, Duke of Saxony, and his wife Sidonie Podiebrad, princess of Bohemia. When Albert died in 1500, his eldest son Georg succeeded to the Duchy of Saxony, and Heinrich became Lord of Friesland.

Saxon rule of Friesland was disturbed by constant revolts. Consequently, Heinrich, who was of a rather inert disposition, gave up his title there. In 1505 Heinrich ceded Friesland to Georg, in return for an annuity and the districts of Wolkenstein and Freiberg, where Heinrich made his residence.

In 1517, Martin Luther started the Protestant Reformation in Germany, and a few years later Heinrich converted to Lutheranism. Georg remained a devout Catholic. Both of Georg's sons predeceased him without issue.

When Georg's second son died in 1539, Heinrich (a Protestant) became heir presumptive to the Duchy under the Act of Settlement of 1499. To prevent a Protestant succession, Georg tried to override his father's will, disinherit Heinrich, and bequeath the Duchy to Ferdinand, brother of Charles V. But Georg died only two months later, and Heinrich succeeded to the Duchy.

He was then 66 years old, and reigned for only two years. Heinrich made Lutheranism the state religion of the Duchy of Saxony.

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