An epithet is a title or nickname given to a person whilst living or posthumously. It denotes a major aspect of their personality, achievements, skills, or attributes.

Overview
In Norse culture, and in other Germanics such as the Anglo-Saxons, it was widespread to highlight noted people or noted characteristics about someone. All Norsemen are born with the name of their father added as their surname, for example Ragnar Sigurdsson and Bjorn Ragnarsson. However, in the event of a notable occurrence or personal instance, the use of an epithet overrides the familial designation.
In Vikings
After fighting bravely in Wessex, Ragnar gave Bjorn the title "Ironside," denoting how he suffered no injuries as if his skin was "hard as iron."
Ragnar himself was called "Lothbrok," meaning "hairy breeches." According to legend, he defeated a mighty serpent that was terrorizing his village by use of trousers made of animal hides. The serpent was not able to bite him while he wore them.
Bjorn's brother, Ivar, was named "Boneless" by Ragnar due to his disability. Sigurd was named "Snake-in-the-Eye" by his mother, Aslaug, due to a congenital iris shape that resembled a snake.
King Harald was called "Finehair," possibly due to having fair hair. Meanwhile, the meaning of the name of his brother Halfdan "the Black" is unknown. Their associate, Egil "the Bastard," could be due to him being either illegitimately born or estranged from his father.
History
The Medieval Christians used only a single name. The origin of this custom is in the fall of the Roman Empire. The Romans used three names. The proper name was first and was called "praenomen." Then came the "nomen," which designated the clan. The last name designated the family and was known as "cognomen." Some Romans added a fourth name, the "agonome," to commemorate illustrious acts or memorable events. When the fall of the Roman Empire occurred, family names became confused and it seems that the use of only one name became customary once again.
In the Catholic kingdoms of Europe, the modern concept of a "surname" still did not exist because is a relatively recent historical development, which evolved from a medieval naming practice called a "byname." Based on an individual's occupation or area of residence, a byname would be used in situations where more than one person had the same name. This process parallels, and is analogous, to that of the nobility, who in many cases used the name of the lands of their respective family.
Medieval Greeks of the Byzantine Empire were starting to develop family names in the time period that the series takes place. Hereditary family names, or surnames, began to be used by elites in the Byzantine period. However, well into the 9th century they were rare. Family names came from placenames, nicknames, or occupations.
The Mohammedan Arabs have a long and complex naming system when compared to the Norsemen and Medieval Christians. The "ism" is the given, first, or personal name. The "kunya" refers to the first-born of the person and is used as a substitute for the ism. For example, أبو كريم "Abu (father) Karim" for "father of Karim," and أم كريم "Umm Karim"for "mother of Karim." A "kunya" precedes the "ism" when it does not replace it. A "nasab" is a patronymic, or a series of patronymics. It indicates the ancestry of the person by the word ابن "ibn" (sometimes "bin") meaning son, or "bint" meaning daughter. Several nasab can follow in a chain, to trace the ancestry through the times. The "laqab" is intended to describe the person. So, for example, in the name of the famous Abbasid Caliph Haroun al-Rashid (described in Thousand and One Nights), Haroun is the Arabic form of the name Aaron, and "al-Rashid" means "the righteous" or "the well-guided." The "nisba" describes the occupation of the person, geographical location of the house, or descent (tribe, family, etc.). "Nisba" will follow the family through several generations. The "nisba," among the components of the Arabic name, is perhaps the one that most resembles the surnames of the West.
Historical Examples
Many Germanic figures had epithets:
- Erik the Red: A Norse warrior who discovered Iceland.
- Thorgils Skarthi: A Norse warrior who is said to have founded the Yorkshire town of Scarborough.
- Various Norse kings of the Viking Age include:
- Gorm the Old
- Sweyn Forkbeard
- Harald Bluetooth
- Harold Harefoot
- Harald Hardrada
Anglo-Saxons with epithets were:
- King Alfred the Great of Wessex: Though this was given to him by later scholars.
- King Edward the Elder of the Anglo-Saxons: As an older King Edward, vis-à-vis King Edward the Martyr, who ruled decades later.
- King Edgar the Peaceful of England: Because he solved disputes via peaceful means.
- King Aethelred the Unready of England: Meaning "bad counsel," but a mistranslation of the Old English word "unread," as in bad counsel as a pun on his name meaning noble counsel.
- King Edmund Ironside: Son of King Aethelred the Unready, named for his fighting prowess.
- King Edward the Confessor: A younger son of King Aethelred the Unready, named "the Confessor" due to his piety and veneration as a saint.
- Edric Streona: An English noble who was deemed a traitor for siding with Cnut the Great against King Edmund Ironside. "Streona" was a label meaning "treacherous."