Ceausescu, whose secret police was responsible for severe repression and human rights abuses, was convicted of genocide in 1989 and was executed by firing squad along with his wife Elena.
His rise to power saw his government become one of the most repressive in Eastern Europe - that saw Romanians suffer severe food, medicine and water shortages.
Despite his tyrannical reign he was afforded a state visit to the UK in 1978.
Royal biographer Robert Hardman revealed the Queen was not happy with the visit - even hiding in a bush to avoid speaking with the brutal dictator.
While speaking about Donald Trump’s upcoming state visit to the UK, Mr Hardman told BBC Radio 4’s Today programme: "When you look back over her [the Queen’s] state visitors, this one is going to be a walk in the park compared to 1978 when she had the Ceausescus, probably the worst state visit of her reign.
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“Nobody wanted them - even days before the foreign secretary was heard saying ‘why is this visit happening? I don’t want these people’.
“But the Queen had to have them stay and found them so disagreeable, when she found them once walking through the palace gardens she hid behind a bush in order to avoid talking to them.
“That’s certainly not going to happen with Donald Trump."
While the Queen won’t be hiding from the President in June, she will not be hosting him for an overnight stay as the palace is undergoing building works.
Trump will also not be having a carriage procession - at the insistence of US security chiefs, who said that “we can’t have our President riding through a foreign capital in a vehicle made out of leather and wood and built in the 19th century”.
Mr Hardman added that Trump will be one of the “easiest state visitors the Queen has ever had”.