Frederick I, the Victorious (der Siegreiche) (1 August 1425, Heidelberg - 12 December 1476, Heidelberg) was a Count Palatine of the Rhine and Elector Palatine from the House of Wittelsbach in 1451-76.
He ruled the Electoral Palatinate after the death of his brother Louis IV as regent for his nephew Philip, Elector Palatine. He adopted his nephew in 1451 and refused to marry. From this "Arrogation," he claimed the right to be the legitimate elector. As this action was against imperial law, Emperor Frederick III refused to confirm Frederick's status. However, the emperor did not manage to displace Frederick who was an able strategist and allied with Louis IX, Duke of Bavaria.
Frederick was also successful against other opponents such as the emperor's party follower Albrecht III Achilles, Elector of Brandenburg and Diether von Isenburg, the archbishop of Mainz, and increased his territory. With the Battle of Seckenheim during the Bavarian War (1459-63) Frederick captured his antagonists Bishop George of Baden, Charles I, Margrave of Baden-Baden and Ulrich V, Count of Württemberg.