House of Gorizia
Otto was born in the Austrian capital Vienna, the youngest son of King Albert I of Germany and Elizabeth of Carinthia, a member of the House of Gorizia-Tyrol ("Meinhardiner"). His elder brothers were Rudolf III, who became King of Bohemia in 1306, Frederick the Fair, elected King of the Romans in opposition to Louis the Bavarian in 1314, the Austrian dukes Leopold I and Albert II as well as Henry the Friendly.