Peter I (Serbian Cyrillic: Петар I Карађорђевић, romanized: Petar I Кarađorđević; 11 July [O.S. 29 June] 1844 – 16 August 1921) reigned as the last king of Serbia (1903–1918) and as the first king of the Serbs, Croats and Slovenes (1918–1921). Since he was the king of Serbia during a period of great Serbian military success, he was remembered by the Serbian people as King Peter the Liberator, and also as Old King.
