Vaino I (May 1, 1868-May 28, 1940) was King of Finland. Prince of Hesse-Kassel, Germany. On January 25, 1893, Friedrich Karl married Margaret, the granddaughter of Queen Victoria and the sister of Kaiser Wilhelm II of Germany (1872 - 1954). Since then, he has close relations with the German royal family. In August 1918, the Finnish Parliament voted to elect Prince Friedrich Karl as king, with the royal title "Vaino I".

After postponing his arrival in Finland, he informed the Finns on December 14 that he had decided not to accept the throne. The Finnish monarchy ended in just two months. On May 28, 1940, Friedrich Karl died in the palace of the former Hessian elector in Kassel.