Denmark: Queen Margrethe II
The United Kingdom's Queen Elizabeth II isn't the only reigning Monarch, who is a fierce female. Denmark (and Greenland) is ruled by Her Majesty Queen Margrethe II (and has been since 1972) and she's not going anywhere anytime time soon.
The Queen is married to HRH Prince Henrik, and she has been since 1967. Together they have two children, the eldest being HRH Crown Prince Frederik — who will take over the Monarchy eventually — who is married to Mary Elizabeth (who now has the title of HRH Crown Princess), and together they have four children. Their second son is HRH Prince Joachim, who is married to Princess Marie, and they too have four children.