Frederick IV, Elector Palatine of the Rhine (; 5 March 1574 Р19 September 1610), only surviving son of Louis VI, Elector Palatine and Elisabeth of Hesse, called "Frederick the Righteous" (; French: Fr̩d̩ric IV le juste).
Born in Amberg, his father died in October 1583 and Frederick came under the guardianship of his uncle, John Casimir, an ardent Calvinist, who ruled as regent until his death. The Calvinist mathematician and astronomer Bartholemaeus Pitiscus served as Frederick's tutor and later became court preacher.
In January 1592, John Casimir died and the 17-year-old Frederick assumed control of the government of the Electorate of the Palatinate. Frederick continued John Casimir's anti-Catholic measures and in 1608 became the head of the Protestant military alliance known as the Protestant Union. Thus, he supported Protestant interests in the War of the Julich Succession. He soon fell prey to alcoholism, leaving state matters largely to his chief minister Christian of Anhalt. Frederick IV died in 1610 in Heidelberg.
In 1593, Frederick married Louise Juliana of Nassau, the daughter of William I of Orange and Charlotte de Bourbon-Monpensier. They had eight children: