BBC just said that the euro was used by this government entity and seems to be the only non EU place where the Euro is the currency in daily use (there could be more than one but i can't think of any other possibilities)

??? Guesses?

There are several places fitting this description :
Andorra,
Kosovo,
Monaco,
Montenegro,
San Marino,
Vatican

Iran?

Andorra, Montenegro, and Kosovo use the Euro as do Vatican City, Monaco, and San Marino. None of them are members of the EU.

Well BBC mentioned Kosovo

Montenegro is the only other one fitting the description it seems as Andorra, San Marino, Vatican are part of EU thru accords - not officially but abide by France/Spain (who really rule Andorra) and France - which kind of rules Monaco and Italian enclaves - i realized those entities used the euro.

I wonder if Kosovo and Montenegro are the only non EU or EU enclaves that use the Euro?

Benin, Burkina Faso, Cote D'Ivoire, Guinea-Bissau, Mali, Niger, Senegal, Togo, Cameroon, Chad, Congo, Equatorial-Guined, Gabon.

The Euro is now the most widely-circulated currency on earth apparently.

yes indeedy perhaps - a surprise that all those countries have the euro - those seem mainly ex French colonies that were using a similar currency based on franc

not sure but that may be the reason

Western african (Bénin, Mali, ....) countries use the Franc CFA, not the Euro

They issue own bills to make it look nice

But the franc CFA is tied with the Euro