To the people of the UK, she is Queen Elizabeth II.
But her full title is in fact Elizabeth II, by the Grace of God, of the United Kingdom of Great Britain and Northern Ireland and of her other realms and territories Queen, Head of the Commonwealth, Defender of the Faith.
That's a bit of a mouthful, isn't it?!
And if that weren't enough, you might also be interested to know that the Queen's full name is also quite long, being Elizabeth Alexandra Mary Windsor.
Over the years Her Majesty has also been given several nicknames - Her husband, the Duke of Edinburgh is said to call her by pet names such as 'cabbage' and 'sausage', while as a child her family referred to her as Lilibet.
But the most bizarre nickname she has is thanks to her grandson, Prince William.
Apparently, when he was younger, William would call The Queen 'Gary'.
It's not exactly a name you'd expect to be given to royalty, but it seems there was a cute reason for it - he couldn't pronounce 'Granny' properly.
Columnist Richard Kay revealed how the young prince began bawling "Gary, Gary" after falling over in Buckingham Palace once as a child.
Asked who Gary was as she picked up her grandson, the Queen replied: "I'm Gary. He hasn't learned to say granny yet."
Flash forward to today and it seems William's son, George has followed in his father's footsteps.
In an interview with ITV in 2016, the Duchess of Cambridge revealed that age two, Prince George had started using a nickname for The Queen as well.
She said he called his great-grandmother 'Gan-Gan' and it's believed Princess Charlotte and Prince Louis do the same.
How sweet!
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