Otto of Greece

Otto was a Bavarian prince who ruled as King of Greece from the establishment of the monarchy on 27 May 1832, under the Convention of London, until he was deposed on 23 October 1862.

The second son of King Ludwig I of Bavaria, Otto ascended the newly created throne of Greece at age 17. 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 insurrection, Otto granted a constitution in 1843.

Source: Wikipedia