King of Hungary

The Apostolic King of Hungary is the sovereign of the Kingdom of Hungary and its subsidiary Kingdom of Croatia, from the House of Habsburg-Lorraine and in personal union with the German Empire.

History
In 1515, Emperor Maximilian of the HRE and King Vladislaus II would agree a mutual succession treaty at the First Congress of Vienna. As part of this treaty, Vladislaus' daughter Anne would be married to Maximilian's grandson and heir Charles, while his son Louis would marry Charles' sister, Mary. Vladislaus would die in March the following year and Louis succeeded him, while Charles would succeed his grandfather as Emperor in 1521.