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King George VI and Queen Elizabeth, The Queen Mother -

King George VI and Elizabeth Bowes-Lyon had a reasonable family distance between them. They were 13th cousins.

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King George V and Queen Mary -

George V and Mary of Teck shared a great-grandparent, making them second cousins.  

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William and Kate -

Kate Middleton might be a commoner, but she is still related to Prince William. They are actually 11th cousins once removed. 

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William and Kate -

All because of Sir William Blakiston, a Baronet whose peerage Kate Middleton didn't inherit.

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King Edward VII and Queen Alexandra -

Following the footsteps of his mother (Queen Victoria), King Edward VII also married his cousin, though he and Alexandra of Denmark were third cousins.

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Queen Victoria and Prince Albert -

Queen Victoria and Prince Albert had the same grandfather, Francis, Duke of Saxe-Coburg-Saalfeld. This makes them first cousins.

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Harry and Meghan - This might come as a surprise for many people, but Meghan Markle and Prince Harry are reportedly distant cousins.

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Harry and Meghan -

The couple is related via the High Sheriff of County Durham, Ralph Bowes, a 15th century ancestor of the Queen Mother.

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Charles and Diana -

Prince Charles and Lady Diana Spencer were actually seventh cousins once removed.

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Prince Edward and Sophie Rhys-Jones -

The Earl of Wessex is married to Sophie Rhys-Jones. They are 11th cousins.

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Queen Elizabeth II and Prince Philip -

Queen Elizabeth II and Prince Philip are both related through Queen Victoria. This makes them third cousins.

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Queen Elizabeth II and Prince Philip -

But they're also both related to King Christian IX of Denmark. Prince Philip had the same great-grandfather as Queen Elizabeth's father. So, this makes them also second cousins once removed.

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King George IV and Caroline of Brunswick -

King George IV and Caroline of Brunswick were first cousins. They married in 1795, but separated one year later.

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Philip II of Spain and Queen Mary I of England -

Philip II of Spain and his wife were first cousins once removed.

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Henry VII and Elizabeth of York -

King Henry VII married his third cousin, Elizabeth of York. 

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The Spanish Habsburgs -

The House of Habsburg is particularly known for intermarriage. They're famed for a genetic trait known as mandibular prognathism (pronounced jaw) as a result.

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The Spanish Habsburgs -

Intermarriage in the family led to some really complex and bizarre situations. For instance, Charles II of Spain's mother, Mariana of Austria, was also the niece of his father, Philip IV of Spain.

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Empress Elisabeth and Emperor Franz Joseph I of Austria -

The emperor married his 16-year-old first cousin, famously known as Sisi.

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Francis II, Holy Roman Emperor and Maria Theresa of Naples and Sicily -

They both had the same set of grandparents, making them double first cousins.

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Maria I of Portugal and Pedro III of Portugal -

Maria I of Portugal married her uncle, Pedro, who was her father's brother.

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Princess Victoria Melita -

Princess Victoria Melita married her first cousin, Grand Duke Ernest of Hesse. She then got divorced and married another cousin, the Grand Duke Kirill Vladimirovich of Russia.

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The Guangxu Emperor -

The Guangxu Emperor, from China, married his first cousin, Xiao Ding Jing.

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Chulalongkorn, King of Siam -

It is estimated that Chulalongkorn, King of Siam (Thailand) had 153 wives, consorts, and concubines. Among them were his four half-sisters.

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King Kauikeaouli (Kamehameha III) and Princess Nahi'ena'ena -

It is believed that Kamehameha (the founder and first ruler of the Kingdom of Hawaii) and his sister Nahi'ena'ena married in secret.

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Cleopatra and Ptolemy XIII -

The two were brother and sister and became co-rulers of Ancient Egypt.

See also: Iconic women who married into royalty

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