A Queen Consort is the wife and consort of a reigning king.
In contrast, the husband of a reigning queen is not called 'King Consort'. Such a husband is popularly called the prince consort; however, this title has so far been granted officially only to Prince Albert, husband of Queen Victoria of the United Kingdom. In the British system, a male consort is not even automatically a prince until he is so created by the sovereign.
In general, the consorts of monarchs have no constitutional status or power, merely the title.
There are a few cases in which a married couple ruled a kingdom jointly. Ferdinand II of Aragon and his wife Isabella, in her own right Isabella I of Castile, ruled their kingdoms as one dominion, and Ferdinand was also called Ferdinand V of Castile. However, the two kingdoms would not be de jure united until the monarchs' grandson Charles V, Holy Roman Emperor acceded to both thrones as Charles I of Spain.
The daughter of James II of England, Queen Mary II, married William of Orange; although Mary was the heiress to the throne, she and William chose to reign together and were made co-monarchs by Parliament, with William becoming King.
There have also been a number of cases when the queen consort of a deceased king (the queen dowager or queen mother) has served as regent while her child, the heir to the throne, was still a minor; for example Catherine de Medici.
Besides these examples, there have been many cases of queen consorts being shrewd stateswomen and, albeit unofficially, being one of the king's major advisors. In some cases, the queen consort has been the chief power behind the throne.
Examples of Queens Consort
Because queens consort lack an ordinal with which to distinguish between them, many historical texts and encyclopædias refer to deceased consorts by their pre-marital or maiden name or title, not by their marital royal title.