Otto, Royal Prince of Bavaria, then Othon, King of Greece (Greek: Ὄθων, Βασιλεὺς τῆς Ἑλλάδος, Óthon, Vasiléfs tis Elládos; 1 June 1815 - 26 July 1867) was made the first modern King of Greece in 1832 under the Convention of London, whereby Greece became a new kingdom under the protection of the Great Powers (the United Kingdom, France and the Russian Empire).
The second son of the philhellene King Ludwig I of Bavaria, Otto ascended the newly created throne of Greece while still a minor. His government was initially run by a three-man regency council made up of Bavarian court officials. Upon reaching his majority, Otto removed the regents when they proved unpopular with the people and he ruled as an absolute monarch. Eventually his subjects' demands for a Constitution proved overwhelming and in the face of an armed but peaceful insurrection, Otto granted a Constitution in 1843.