Maximilian I, Holy Roman Emperor

Maximilian was the only surviving son of Frederick III and ran a joint government with his father from 1486 until Frederick's death in 1493. His 1477 marriage to Mary, Duchess of Burgundy expanded Habsburg influence through war, though the family lost its Swiss lands to the Swiss Confederacy. By marrying his son Philip the Handsome to Joanna of Castile in 1496, he positioned his grandson Charles V to hold both Spanish thrones. Called "Heart of steel" for either courage or ruthlessness, he became known as "the last knight" - though scholars still argue whether he was a medieval dreamer or a calculating Renaissance prince who leveraged loans to lift his family to the peak of dynastic power. Through an "unprecedented" image-building program with scholars and artists, he constructed what one historian calls a "virtual royal self" of "unmatched" quality, spawning a "Maximilian industry" that outlasted him by centuries.