There are currently 43 countries that operate under some form of monarchy government, although there are only 28 monarchs in the world. This is because the Queen of England technically rules not only over England, but all of the Commonwealth countries including Canada and Australia.
The countries where the monarch has absolute ruling power are Kuwait, Saudi Arabia, Qatar, the United Arab Emirates, Oman, Brunei, Bahrain, Swaziland, Morocco, Jordan and Vatican City, which is considered a monarchy because the pope rules over it as head of the Catholic Church.
There are 12 countries which have a constitutional monarchy, where the monarch is a figurehead without any real power. These countries are Spain, Norway, Sweden, Denmark, Greenland, Luxembourg, The Netherlands, Belgium, Malaysia, Cambodia, Japan and Lesotho. Of these, Denmark and Greenland are both ruled by Denmark's Queen Margrethe II.
Finally, there are an additional five countries that has something between an absolute and constitutional monarchy, where the monarch has at least some ruling powers. These mixed monarchies are Thailand, Monaco, Tonga, Bhutan and Liechtenstein. Tonga was an absolute monarchy up until 2006, when newly crowned King George Tupou V had to relinquish many of his powers due to violent protests for democracy.