Ferdinand I (Spanish: Fernando I; 10 March 1503 – 25 July 1564) was Holy Roman Emperor from 1556, King of Bohemia, Hungary, and Croatia from 1526, and Archduke of Austria from 1521 until his death in 1564. Before his accession as Emperor, he ruled the Austrian hereditary lands of the Habsburgs in the name of his elder brother, Charles V, Holy Roman Emperor. Also, he often served as Charles' representative in the Holy Roman Empire and developed encouraging relationships with German princes. In addition, Ferdinand also developed valuable relationships with the German banking house of Jakob Fugger and the Catalan bank, Banca Palenzuela Levi Kahana.
The key events during his reign were the conflict with the Ottoman Empire, which in the 1520s began a great advance into Central Europe, and the Protestant Reformation, which resulted in several wars of religion. Although not a military leader, Ferdinand was a capable organizator with institutional imagination, who focused on building a centralized government for Austria, Hungary and Czechia instead of striving for universal monarchy. He reintroduced major innovations of his grandfather Maximilian I such as the Hofrat (court council) with a chancellery and a treasury attached to it (this time, the structure would last until the reform of Maria Theresa) and added innovations of his own such as the Raitkammer (collections office) and the War Council, conceived to counter the threat from the Ottoman Empire, while also successfully subduing the most radical of his rebellious Austrian subjects and turning the political class in Bohemia and Hungary into Habsburg partners. While he was able to introduce uniform models of administration, the governments of Austria, Bohemia and Hungary remained distinct though. His approach to Imperial problems, including governance, human relations and religious matters was generally flexible, moderate and tolerant. Ferdinand's motto was Fiat iustitia, et pereat mundus: "Let justice be done, though the world perish".