Prince Aimone, 4th Duke of Aosta was a prince of Italy's reigning House of Savoy and an officer of the Royal Italian Navy. The second son of Prince Emanuele Filiberto, Duke of Aosta he was granted the title Duke of Spoleto on 22 September 1904. He inherited the title Duke of Aosta on 3 March 1942 following the death of his brother Prince Amedeo, in a British prisoner of war camp in Nairobi.
From 18 May 1941 to 31 July 1943 he was designated King of the Independent State of Croatia though he never ruled there. He formally accepted the position and took the name Tomislav II, after the first Croatian king. Later, however, he refused to assume the kingship in protest of the Italian annexation of the Dalmatia region, and is therefore referred to in some sources as king designate. Regardless, many sources refer to him as Tomislav II, King of Croatia, and the nominal head of the NDH during its first two years.
After the dismissal of Mussolini on 25 July 1943, the prince abdicated on 31 July as king on the orders of Victor Emmanuel III.