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Heir apparent -

There are two types of heirs: apparent and presumptive. An heir apparent is the first in the line of succession and is not at risk of being displaced. 

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Heir presumptive -

An heir presumptive may be at risk of losing the claim to the throne if another sibling is born. Now, let's take a look at some of the heirs, both apparent and presumptive, who waited a long time for the throne. 

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King Norodom Sihamoni -

Norodom Sihamoni ascended to the Cambodian throne in 2004, shortly after the abdication of his father. Sihamoni was an heir for 11 years in total.

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Queen Elizabeth II -

Queen Elizabeth II was not the first in line to the throne, because her father did not become king until his brother abdicated. Still, after being the heir for 16 years, Elizabeth was crowned queen. 

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Hussein of Jordan -

Hussein became king of Jordan in 1952 after his father, King Talal, suddenly passed away. He waited 16 years to rule. 

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King Bhumibol Adulyadej -

King Rama IX waited 18 years to rule Thailand. Bhumibol Adulyadej became king in 1946 after the sudden passing of his brother, King Ananda Mahidol.

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Queen Victoria -

Queen Victoria was crowned at age 18 after her uncle died. She wasn't expecting to sit on the throne, but the sudden death of William IV dictated otherwise. 

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Emperor Franz Joseph I -

Franz Joseph waited for 18 years before ruling as emperor. He ascended to power after his uncle, Emperor Ferdinand I, abdicated.

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King Carl XVI Gustaf -

King Carl XVI Gustaf ascended to the throne in 1973 after his grandfather King Gustaf VI Adolf died. He waited 23 years to become king. 

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Albert II of Belgium -

Albert became king in 1993 after his brother, King Baudouin, passed away. Albert II of Belgium waited 23 years for the crown. 

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Frederick Louis -

The heir apparent of King George II waited 23 years for his chance to rule Britain. Frederick Louis died before his father, so it never happened. 

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King Edward VIII -

King Edward VIII is best known for abdicating the British throne less than a year after his coronation. Edward was the heir to the throne for 25 years. 

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King Charles IV of Spain -

Charles was heir for 29 years. He eventually became king after his brother, Ferdinand, renounced his right to the Spanish crown. 

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Wilhelm, German Crown Prince -

Wilhelm became the Crown Prince at the age of six, and for 30 years he was the next in line to the throne. In 1918 the monarchy was abolished in Germany so Wilhelm never became kaiser. 

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Rudolf, Crown Prince of Austria -

Rudolf was born into nobility as the Crown Prince of Austria. Rudolf and his lover, Baroness Marie Alexandrine von Vetsera of Austria, were found dead in 1889. This was the end of his 30-year wait to claim the throne. 

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Edward the Black Prince -

The heir apparent of King Edward III of England waited for 33 years for the crown but died before his father. Edward's son, Richard II, became king.

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Louis, Dauphin Of France -

The eldest son of King Louis XV of France waited for 36 years to become king. Sadly, he contracted tuberculosis and died in 1765 before he could ascend to the throne. 

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Emperor Akihito -

Akihito was 19 when he became heir apparent to the Chrysanthemum Throne in 1952. In total, he waited 37 years until 1989 to become the 125th emperor of Japan.

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Queen Juliana -

Queen Juliana of the Netherlands was heir to the throne for 39 years, from 1909 to 1948. The Queen of the Netherlands ruled from 1948 until her abdication in 1980.

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Isabel, Princess Imperial of Brazil -

Isabel was the heir presumptive, meaning that any sons of Emperor Pedro II would assume the throne before her. In total, she waited 41 years, but Brazil's Emperor was deposed in 1889.

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Vajiralongkorn -

Rama X was heir to the Thai throne from 1972 to 2016. Vajiralongkorn patiently waited for 44 years until the death of his father, King Bhumibol Adulyadej, to rule. 

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Christian, Prince-Elect of Denmark -

Christian the Prince-Elect would have ruled as Christian V but died before he ascended to the throne. Christian waited 44 years for the Norwegian crown and 39 for the Danish one. 

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King Felipe VI -

The Spanish king waited 46 years as the next in line before he ascended to the throne in 2014. He did so after the abdication of his father, King Juan Carlos I.

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Louis, Grand Dauphin -

Louis, Grand Dauphin, was heir to the French throne from 1661 until 1711. His nearly half-a-decade wait ended with his death, so he never became king. 

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George IV -

There have been a few Princes of Wales over the years, patiently waiting for their time to rule Britain. George IV was one of them. In total, he waited for 58 years to ascend to the throne. 

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King Edward VII -

The eldest son of Queen Victoria had to wait 59 years to become king. The Prince of Wales ascended to the throne after his mother passed away in 1901.

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James Francis Edward Stuart -

James Francis Edward Stuart was briefly heir apparent from 1688 to 1689. He then claimed the British throne from 1701 to 1766, but never became king. In total, the 'Old Pretender' waited for 65 years for his moment, but it never came.

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King Charles III -

King Charles holds the Guinness World Record for the longest heir apparent wait ever. Charles was the first in the line of succession for 70 years and 214 days.

Sources: (Ranker) (Mental Floss) (Guinness World Records) 

See also: The royal family's secret travel rules

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