Amadeo I, also known as Amadeus, was an Italian prince who reigned as King of Spain from 1870 to 1873. The only king of Spain to come from the House of Savoy, he was the second son of Victor Emmanuel II of Italy and was known for most of his life as the Duke of Aosta, the usual title for a second son in the Savoyard dynasty.

Adelaide of Austria was Queen of Sardinia by marriage to Victor Emmanuel II of Sardinia, future King of Italy, from 1849 until 1855 when she died as a result of gastroenteritis. She was the mother of Umberto I of Italy.