The Queen is usually a reference to a reigning queen regnant. In anglosphere and various other countries "the Queen" is usually a synonym for Elizabeth II of the United Kingdom. Current queens regnant are:

Beatrix of the Netherlands
Elizabeth II of the United Kingdom
Margrethe II of Denmark Beatrix (born January 31, 1938 as Beatrix Wilhelmina Armgard, Princess of the Netherlands, Princess of Orange-Nassau, Princess of Lippe-Biesterfeld) has been the Queen regnant of the Kingdom of the Netherlands since April 30, 1980. ... Elizabeth II (Elizabeth Alexandra Mary Windsor; born 21 April 1926) is Queen of sixteen sovereign states, holding each crown and title equally. ... Margrethe II (Margrethe Alexandrine Þórhildur Ingrid) (born 16 April 1940) is the Queen regnant of Denmark. ...