List of movements that dispute the legitimacy of a reigning monarch

This is a list of movements that dispute the legitimacy of a reigning monarch. It includes those movements that believe a current monarch is on the throne unlawfully, but does not include groups that oppose monarchy generally (such as those that favor replacing a monarchy with a republican system of government).

*Carlism is a movement in that seeks the establishment of another line of the Bourbon family on the Spanish throne, in preference to the current Spanish King, Juan Carlos I. Carlists dispute that Fernando VII had the authority to change the Spanish monarchy's line of succession by issuing the Pragmatica Sanción and claim that such document was without legal effect. The Pragmatica Sanción resulted in Fernando's daughter Isabel II, rather than his brother, Infante Carlos, becoming the Spanish monarch.
*Jacobitism asserts that the Glorious Revolution was unlawful and effected a "de facto" but not "de jure" change in the line of succession to the British Monarchy. In the Jacobite view, William and Mary of Orange and their successors were never legitimate British rulers. Instead, the lawful king or queen of England and Scotland has continued to be the heir-general of the House of Stuart. The current Jacobite King is Franz, Duke of Bavaria, or 'King Francis II'.
*Sedevacantism holds that the current Roman Catholic pope, Benedict XVI, is illegitimate. More generally, sedevacantists believe that the chair of St. Peter has been vacant since the death of Pope Pius XII in 1958 or Pope John XXIII in 1963 and that subsequent holders of the papal throne have not been true popes. This movement is largely driven by opposition to liturgical reforms introduced by the Second Vatican Council, especially replacement of the Tridentine Mass with the Mass of Paul VI and authorizing the saying of the Mass in vernacular languages rather than ecclesiastical Latin.