Many past and present European monarchies have reserved titles used just by the heir apparent to the throne. The famous example of this is Charles, Prince of Wales, heir to the British throne. Many heir have had “crown prince” as their title.

Titles in present and former kingdoms

Prince of Wales, Earl of Chester, Duke of Cornwall, Duke of Rothesay, Earl of Carrick, Baron of Renfrew, Lord of the Isles and Prince and Great Steward of Scotland 
Dauphin of France, Used by the heir to the French throne while the country was a monarchy. 
Duke of Brabant, Used by the heir to the King of the Belgians. The title of Crown Prince of Belgium was also used but later abandoned having been used once by Crown Prince Louis Philippe. 
Crown Prince of Prussia & German crown prince, used by the heir to the German Empire. 
 Tsarevich of Russia, used by the heir to the Russian Imperial throne. 
 Prince of Asturias, used by the heir to the Spanish throne.  

Crown Prince of Sweden, used in Sweden. The present heir is Victoria, Crown Princess of Sweden who holds the title in her own right.
Crown Prince of Norway. Used in Norway. 
Prince of Orange used by the heir to the Kingdom of the Netherlands. 
Crown Prince of Denmark. Used by the heir to the Danish throne. 
Crown Prince of Greece and sometimes Duke of Sparta. Used by the heir to the Greek throne. 
King of the Romans, used by the heir of the Holy Roman Emperor and thus the person expected to rule over the Holy Roman Empire. 
While Portugal was a monarchy the title of Prince of Brazil  which took the place of Prince of Beira. The title of Prince of Brazil was used along side of Duke of Braganza, such as José, Prince of Brazil.
The Crown Prince of Hanover.

Other states

General
Hereditary Prince of Monaco. Used by the heir to the Principality of Monaco. 
Hereditary Prince of Liechtenstein used by the heir to the Principality of Liechtenstein. 
Hereditary Grand Duke of Luxembourg. Used by the heir to the Grand Duchy of Luxembourg.

German states
Prior to the unification of Germany, the area was made up of dozens of small principalities such as Duchies and Grand Duchies and most of them used the titles of Hereditary, Grand Duke or Hereditary Prince [followed by name of state] such as:

His Royal Highness The Hereditary Prince of Baden the heir to the Grand Duchy of Baden.
His Royal Highness The Hereditary Grand Duke of Hesse heir to the Grand Duchy of Hesse.
His Royal Highness The Hereditary Grand Duke of Oldenburg heir to the Grand Duchy of Oldenburg. 
 His Serene Highness The Hereditary Prince of the Palatinate heir to the Electorate of the Palatinate. 
His Highness The Hereditary Prince of Saxe-Coburg and Gotha heir to the Duchy of Saxe-Coburg and Gotha.
His Royal Highness The Hereditary Grand Duke of Mecklenburg-Schwerin. heir to the Grand Duchy of Mecklenburg-Schwerin.
His Serene Highness The Hereditary Prince of Waldeck and Pyrmont heir to the Principality of Waldeck and Pyrmont.

Italian states
Hereditary Prince of Naples. Used by the heir to the Kingdom of Naples prior to its unification  with Sicily in 1825. After which the title Duke of Calabria was used.
Grand Prince of Tuscany, used by the heir to the Grand Duchy of Tuscany.
Prince of Piedmont, Used by the heir to the Duchy of Savoy. When the duchy became the Kingdom of Sardinia, the title Duke of Savoy was also used by the heir to the throne.
Hereditary Prince of Modena. heir to the Duchy of Modena.
Hereditary Prince of Parma heir to the Duchy of Parma.

Examples
Ferdinando de' Medici, Grand Prince of Tuscany known as the Grand Prince all his life as he never succeeded dying before his father. 
Philippe of Belgium present day King of the Belgians who was known as the Duke of Brabant from 1993-2013. 
King Victor Amadeus III of Sardinia was known as the Duke of Savoy from 1726-1773. 
Emperor Wilhelm II - known as the Crown Prince of Prussia & German crown prince for 6 months in 1888. 
Queen Charlotte of Württemberg known as The Hereditary Princess of Württemberg for five months in 1797.

References 
 

Titles
Royalty and nobility