A regnal name, or reign name, is a formal name used by a monarch during his or her reign. Since mediaeval times monarchs have frequently chosen to use a name different to their own personal name when they inherit a throne. The new name is followed by an ordinal to give a unique name for the period when the monarch is on the throne. In parts of Asia, monarchs take era names.

Examples of regnal names

• Prince Albert Edward, Prince of Wales, the Heir Apparent, took the regnal name Edward VII when he became King of the United Kingdom of Great Britain and Ireland in 1901, largely out of deference to his late mother Queen Victoria's wish that no future British monarch be named Albert, following the death of her husband Prince Albert. Furthermore, Prince Albert, Duke of York, the Heir Presumptive, took on the regnal name of King George VI when he inherited the throne in 1936 for the same reason; as he was not the eldest son, he was christened as Albert due to the fact that he had not been expected to become king.

• The first pope to adopt a new name upon elevation to the papacy was John II (Mercurius) in 533. Nearly every pope since John X in the 10th century has used a regnal name different from his given name; e.g. Paul VI (Giovanni Montini), John Paul I (Albino Luciani), John Paul II (Karol Wojtyła), Benedict XVI (Joseph Ratzinger).

• It is rumoured that HRH Prince Charles (Charles Philip Arthur George Mountbatten-Windsor) wishes to assume the regnal name of George VII upon his accession to the throne, in light of the unpopularity of the two previous British kings who reigned using the name Charles: Charles I who was executed for treason, and his son Charles II. The regnal name George is dynastically acceptable to the Windsor family.

• The heir to the Dutch throne, Prince Willem-Alexander, Prince of Orange, said in an interview he would assume the name of Willem IV (William IV) when he accessed the Dutch throne. This is line with the previous Dutch kings William I, William II and William III.

Monarchs who did not choose a different regnal name

Constantine II, former king of the Hellenes (Greece) from 1964-1974, chose to keep his own name when he became king.

Not all monarchs choose a new name when they assume the throne.

For example:

• When Princess Elizabeth as Heir Presumptive became Queen of the United Kingdom of Great Britain and Northern Ireland in 1952, she was asked what name she wished to use, and she responded, "Why, my own name — what else?" There had been speculation that she would take the name of her grandmother, the queen consort Queen Mary, and reign as Queen Mary III. (Her given names are Elizabeth Alexandra Mary.)

• Most current and recent European monarchs have used their first one or two given names, including Albert II of the Belgians, Juan Carlos of Spain, Beatrix of the Netherlands, Margrethe II of Denmark, Carl XVI Gustaf of Sweden, and the former Constantine II of the Hellenes.

• The last two popes who did not adopt a new name as his regnal name were Marcellus II (Marcellus Corvini, 1555) and Adrian VI (Adrian Florisz Boeyens, 1522).

See also

• Temple name
• Posthumous name