Who has the power in an absolute monarchy?

In an absolute monarchy, the King (or Queen) makes the laws, and everybody is supposed to obey them. There have been a few successful absolute monarchies, where the King sincerely did the right things for his people, but most absolute monarchies degenerate when the first spoiled brat becomes King. The monarch is either deposed or he cedes some of his power to a council, parliament or legislature, and the monarch shares power with a elected or appointed circle of advisers.

One example of a relatively-successful "absolute monarchy" would be Richard, the Lion-Hearted, King of England. His younger brother named John was the "Prince John" mocked in Robin Hood legends and stories for the last 800 years. King John was such a failure as "absolute" monarch that in 1215, his nobles and barons assembled at the town of Runnymede, England, and forced King John to relinquish many of his "absolute" powers. In the new order of things, the nobles and barons had certain rights that the King was obliged to respect. This document, called the "Great Charter" or "Magna Carta", ended the absolute monarchy in England.

And since then, no male child who might ascend to the British throne has been named "John" - and likely, none ever will be.

The closest thing to an absolute monarch these days is probably King Salman of Saudi Arabia. Even he is not an "absolute" monarch, being limited by an advisory council of relatives.