Born in 1500, Charles was the grandson of the Habsburg Emperor Maximilian I and of Ferdinand of Aragon and Isabella of Castille. On the death of Ferdinand in 1516, Charles became ruler of a united Spain, to which were added the Habsburg territories when he succeeded Maximilian to the elected title of Holy Roman Emperor in 1519.
He actively defended his territorial interests throughout Europe, invading Italy in 1525, eventually making his peace with the pope, Clement VII, in Bologna in 1530, when the pope crowned him as emperor. He abdicated in 1556, retiring to the monastery at Yuste in northern Spain, and died in 1558.
He was painted by Titian, his favourite portraitist.