Those who are regular watchers of The Crown, you'd know that Prince Philip likes to refer to his wife as 'Lilibet.' It's also been said that he calls her 'sausage' when they are alone.
Her Majesty's great-grandchildren Prince George and Princess Charlotte like to refer to the Queen as 'Gan-Gan,' while William jokingly called her 'Gary' when he was young after struggling with the pronunciation with 'Granny.'
High society gossip columnist Richard Kay in the Daily Mail, 'The Queen was on hand after William fell over at Buckingham Palace, bawling: ‘Gary, Gary’.
'A guest who went to help asked who Gary was, assuming it must be a member of the royal household. ‘I’m Gary,’ explained the Queen, as she scooped him up. ‘He hasn’t learned to say Granny yet'.’
Prince George and Princess Charlotte also apparently have a sweet nickname for Camilla.
The Duchess of Cornwall told Lady Gaga at the 2016 Royal Variety Performance that her grandkids call her 'Gaga'.
Prince Harry sweetly calls his father 'pa' and is often called 'darling boy' in return. This was demonstrated at the prince's wedding, when Prince Charles walked Meghan Markle down the aisle, Harry could be heard thanking his 'pa' and Charles sweetly replying.
Meghan Markle has also been given her own inner circle moniker.
It's been reported that Prince Charles is said to call his daughter-in-law Tungsten, inspired by the tough metal known for its robustness.
According to the Mail, the nickname came from Meghan’s strength and determination, which impressed her new father-in-law.
It's also been revealed that Meghan gave her now-husband Prince Harry a nickname after their first date (which he 'detested').
Gina Nelthorpe-Crowne, a friend of the former Suits star refers to her partner affectionately as 'Haz.'
Prince William may call his wife 'Catherine' in interviews, but in more casual settings, he gives her sweet pet names.
He’s been overheard calling Kate Middleton 'darling', 'babe', and 'poppet', on several occasions.
The royal family also sometimes use pseudonyms to avoid being detected.
While at St. Andrews, Prince William used 'Steve' to avoid drawing attention to himself.
Prince Harry once had a Facebook page under the name 'Spike Wells.'