- Austria: Austria ruled over much of northern Italy, including Lombardy-Venetia, and was determined to maintain its control over these territories.
- France: France had traditionally been a rival of Austria, and was concerned about the prospect of a strong and unified Italy. France also had its own territorial ambitions in Italy, particularly in Savoy and Nice.
- The Papacy: The Pope opposed the unification of Italy because he feared that it would lead to the loss of his temporal power over the Papal States.
- The Kingdom of the Two Sicilies: The Kingdom of the Two Sicilies was the largest state in southern Italy, and its rulers were determined to maintain their independence.
- Various republican and federalist movements: There were a number of different republican and federalist movements in Italy that opposed unification under a monarchy.