FREDERICK III. (1515-1576), elector palatine, sur-named the Pious, eldest son of John II., palatine of Sim-mern, was born in 1515, succeeded his father in 1556, and became elector palatine on the death of Otto Henry in 1559. On his marriage in 1537 to the Lutheran Princess Maria of Brandenburg-Baireuth, he adopted the Protestant faith, and in 1560 he replaced the Lutheran confession and worship by that of the Reformed or Calvinistic, on which account an unsuccessful attempt was made in 1566 by several of the Lutheran princes to obtain an imperial edict against him. He died 26th October 1576.

See Kluckhohn, Friedrich der Fromme, Nordlingen, 1878. Two volumes of his letters were previously edited by Kluckhohn.