Regnal name

A regnal name, regnant name, or reign name is the name used by monarchs and popes during their reigns and subsequently, historically. Since ancient times, some monarchs have chosen to use a different name from their original name when they accede to the monarchy.

The regnal name is usually followed by a regnal number, written as a Roman numeral, to differentiate that monarch from others who have used the same name while ruling the same realm. In some cases, the monarch has more than one regnal name, but the regnal number is based on only one of those names, for example Charles X Gustav of Sweden. If a monarch reigns in more than one realm, they may carry different ordinals in each one, as some realms may have had different numbers of rulers of the same regnal name. For example, the same person was both King James VI of Scotland and King James I of England.

The ordinal is not normally used for the first ruler of the name, but is used in historical references once the name is used again. Thus, Queen Elizabeth I of England was called simply "Elizabeth of England" until the accession of Queen Elizabeth II almost four centuries later in 1952; subsequent historical references to the earlier queen retroactively refer to her as Elizabeth I. However, Tsar Paul I of Russia, King Umberto I of Italy, Emperor Franz Joseph I of Austria, King Juan Carlos I of Spain, Emperor Haile Selassie I of Ethiopia and Pope John Paul I all used the ordinal I (first) during their reigns, even if there was – at least so far in the case of Paul of Russia, Franz Joseph of Austria, Juan Carlos of Spain or Haile Selassie of Ethiopia – never a second ruler with the same name. In spoken English, such names are pronounced as "Elizabeth the First", "George the Sixth", etc.

In some countries in Asia, monarchs took or take era names. While era names as such are not used in many monarchies, sometimes eras are named after a monarch (usually long-lived), or a succession of monarchs of the same name. This is customary; there is no formal or general rule. For example, the whole period during which a succession of four Georges (George I, II, III, and IV) of the Hanoverian dynasty reigned in Great Britain became known as the Georgian era. Conversely, although there were many Edwards, the Edwardian era always refers to the reign of Edward VII at the beginning of the 20th century.

Ancient rulers in many parts of the world took regnal names or throne names which were different from their personal name. This is known to be true, for instance, of several kings of Assyria, and appears to be the case for several kings of Judah. In Ancient Egypt, Pharaohs took a number of names—the praenomen being the most commonly used, on occasion in conjunction with their personal name.

In the Ethiopian Empire, especially during the Solomonic dynasty, many Emperors would take a throne name, though this was not a general practice; a great number of rulers would remain known during their reign by their birth names. Yekuno Amlak, the founder of the Solomonic dynasty, took his father's name, Tasfa Iyasus, as his throne name. Yagbe'u Seyon, his son and heir, took the throne name Salomon after the biblical figure. Amda Seyon took the throne name Gebre Mesqel, "slave of the cross"; Tewodros I was Walda Ambasa, "son of the lion"; Sarwe Iyasus was Mehreka Nañ "distributor of your [the Lord's] mercy"; etc. Tafari Makonnen, the last sovereign Emperor of Ethiopia, took as his throne name Haile Selassie, meaning "Power of the Trinity".

In the various extant traditional states of Nigeria, the regnal names of the titled monarchs, who are known locally as the traditional rulers, serve two very important functions within the monarchical system. Firstly, because in most states all of the legitimate descendants of the first man or woman to arrive at the site of any given community are considered its dynastic heirs, their thrones are usually rotated amongst almost endless pools of contending cousins who all share the names of the founders of their houses as primary surnames. To differentiate them, secondary surnames are also used for the septs of each of the royal families that are eligible for the aforementioned rotations, names that often come from the names of state of the first members of their immediate lineages to rule in their lands. Whenever any of their direct heirs ascend the thrones, they often use their septs' names as reign names as well, using the appropriate ordinals to differentiate themselves from the founders of the said septs. An example of this is found in the kingdom of Lagos, where the Adeniji-Adele family is distinguished from their numerous Adele cousins by the word Adeniji, which was actually the first name of the reigning founder of their branch of the dynasty, the Oba Adeniji Adele II. This distinction notwithstanding, both groups of dynasts (as well as a number of other ones that do not have the name Adele as an official surname, such as that of the Oloye Adekunle Ojora, a prominent nobleman of royal descent) are part of what is known as the Adele Ajosun Ruling House of Lagos.

Regnal names also serve in Nigeria and in much of Africa as chronological markers in much the same way that those of Europe do (e.g. the Victorian era). When a person describes what happened when so and so ruled over any particular place or people, what he or she is actually saying is that an event happened within a finite period of time, one that is equal to the duration of the reign of the monarch in question. Because it is possible (and in fact common, particularly among the southern tribes) for one individual to have several different names and aliases in a single life, a certain degree of uniformity in usage is required if the history of an entire state is to be tied to his or her name. It is for this reason that when new monarchs are enthroned, the uniqueness of their names is usually considered to be a matter of considerable importance (even when it is caused by nothing more than the adding of ordinals to them or the allowing of more than a generation to pass before their subsequent usage). An example of this can be found in the kingdom of Benin, where the throne name of Erediauwa I became the surname of all of his immediate family in the Eweka royal house of the state, thus nominally tying them and their descendants to the era of his reign. This is especially obvious when their branch's name is compared to the last names of the said king's brothers and their heirs, named the Akenzuas after his father Akenzua II, and his uncles and their heirs, named the Ewekas after his grandfather Eweka II.