Kaiser
Kaiser was the title used for the Emperors of Austria and Germany, from the creation of the Austrian Empire in 1806 (after 1867 the Austro-Hungarian Empire) and from the creation of unified Germany in 1871 until the end of World War I when both empires collapsed and became republics. The Holy Roman Emperor was also called "Kaiser". The word "Kaiser" is the German way to say Caesar, the name the ancient Romans used for their Roman Emperor, just as "Tsar" is the Russian way to say it.
In 1873 these three rulers formed a "League of the Three Emperors", also called the Dreikaiserbund.