Archduke of Austria in the context of "Grand duke"

Charles V (24 February 1500 – 21 September 1558) was Holy Roman Emperor and Archduke of Austria from 1519 to 1556, King of Spain (as Charles I) from 1516 to 1556, King of Sicily and Naples from 1516 to 1554, and also Lord of the Netherlands and titular Duke of Burgundy (as Charles II) from 1506 to 1555. He was heir to and then head of the rising House of Habsburg. His dominions in Europe included the Holy Roman Empire, extending from Germany to northern Italy with rule over the Austrian hereditary lands and Burgundian Low Countries, and Spain with its possessions of the southern Italian kingdoms of Sicily, Naples, and Sardinia. In the Americas, he oversaw the continuation of Spanish colonization and a short-lived German colonization. The personal union of the European and American territories he ruled was the first collection of realms labelled "the empire on which the sun never sets".

Charles was born in Flanders to Habsburg Archduke Philip the Handsome, son of Maximilian I, Holy Roman Emperor and Mary of Burgundy, and Joanna of Castile, younger child of Isabella I of Castile and Ferdinand II of Aragon, the Catholic Monarchs of Spain. Heir of his grandparents, Charles inherited his family dominions at a young age. After his father's death in 1506, he inherited the Habsburg Netherlands in the Low Countries. In 1516 he became King of Spain as co-monarch of Castile and Aragon with his mother. Spain's possessions included the Castilian colonies of the West Indies and the Spanish Main, as well as Naples, Sicily, and Sardinia. At the death of his grandfather Maximilian in 1519, he inherited the Austrian hereditary lands and was elected as Holy Roman Emperor. He adopted the Imperial name of Charles V as his main title, and styled himself as a new Charlemagne.

Rudolf II (18 July 1552 – 20 January 1612) was Holy Roman Emperor (1576–1612), King of Hungary and Croatia (as Rudolf I, 1572–1608), King of Bohemia (1575–1608/1611) and Archduke of Austria (1576–1608). He was a member of the House of Habsburg.

Rudolf's legacy has traditionally been viewed in three ways: an ineffectual ruler whose mistakes led directly to the Thirty Years' War; a great and influential patron of Northern Mannerist art; and an intellectual devotee of occult arts and learning which helped seed what would be called the Scientific Revolution. Determined to unify Christendom, he initiated the Long Turkish War (1593–1606) with the Ottoman Empire. Exhausted by war, his citizens in Hungary revolted in the Bocskai Uprising, which led to more authority being given to his brother Matthias. Under his reign, there was a policy of toleration towards Judaism.

Matthias (24 February 1557 – 20 March 1619) was Holy Roman Emperor from 1612 to 1619, Archduke of Austria from 1608 to 1619, King of Hungary and Croatia from 1608 to 1618 and King of Bohemia from 1611 to 1617. His personal motto was Concordia lumine maior ("Unity is stronger in the light").

Matthias played a significant role in the familial opposition of the Habsburgs against his brother Emperor Rudolf II. After gaining power, he showed little political initiative of his own. The course of his politics was determined by Cardinal Melchior Klesl until his fall in 1618. As a consequence of his failed religious and administrative policies, the Bohemian Revolt, the initial theatre of the Thirty Years' War, began during the final year of Matthias' reign.

The Empire of Charles V, also known as the Habsburg Empire, included the Habsburg hereditary lands in central Europe, the kingdoms of Spain, the colonial Spanish Empire, the kingdom of Naples, the Habsburg Netherlands and other territories and principalities across Europe. It is sometimes considered to include, in addition, the kingdoms of Bohemia and Hungary which were held by Charles's brother Ferdinand during his reign. Charles was also Holy Roman Emperor and, as such, was suzerain of the states of the Holy Roman Empire.

The empire was the first to be labelled as "the empire on which the sun never sets", a term used to describe several global empires throughout history. The lands of the empire had in common only the monarch, Charles V, while their boundaries, institutions, and laws remained distinct. Charles's nomenclature as Holy Roman Emperor was Charles V (also Karl V and Carolus V), though earlier in his life he was known by the names of Charles of Ghent (after his birthplace in Flanders), Charles II as Duke of Burgundy, and Charles I as King of Spain (Carlos I) and Archduke of Austria (Karl I). The imperial name prevailed due to the politico-religious primacy held by the Holy Roman Empire among European monarchies since the Middle Ages, which Charles V intended to preserve as part of his (ultimately failed) project to unite Christendom under his leadership.

Ferdinand 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 House of Habsburg in the name of his elder brother, Emperor Charles V, and often served as Charles' representative in developing 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 Ferdinand's 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 organizer with institutional imagination who focused on building a centralized government for Austria, Hungary, and Bohemia 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 Hofkriegsrat, 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. 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".

Isabella of Portugal (Portuguese: Isabel de Portugal; 24 October 1503 – 1 May 1539) was the empress consort of Charles V, Holy Roman Emperor, King of Spain, Archduke of Austria, and Duke of Burgundy. She was Queen of Spain and Germany, and Lady of the Netherlands from 10 March 1526 until her death in 1539, and became Holy Roman Empress and Queen of Italy in February 1530. She acted as regent of Spain during her husband's long absences.