"And although we don't know the truth of these stories, we know of occasions when wise old men have reckoned them to be true."
Snorri Sturluson, Preface to Heimskringla
Legends are stories that are, at least in their beginnings, passed down as “true”, or at least possibly true. Tellers of a legend and their listeners may not necessarily believe in all its details, or even in its truth as a whole, but at least they believe that previous generations thought it was true. Legends often describe events that supposedly happened "long ago".
Their claim to factuality, or at least realism, distinguishes them from folktales, fairy tales and other types of stories that make no claim to be anything other than fiction. Accordingly, legends often have a historical setting, and before the emergence of critical history-writing, legend and history were mostly indistinguishable genres. Legends may feature historical figures, even though the details of the story spun around them are often clearly unreal.
Of course, “legend” has acquired secondary meanings – more often than not, to call something a “legend” means, depending on context, either “it’s awesome” (like in “Living Legend”), or “it’s not true” (like in “historical legend”). This doesn’t actually mean that we don’t believe in legends any more – only that we don’t call them “legends” (at least so long as we believe in them). Such modern day legends may be referred to as Urban Legends.
Legends are related to (and sometimes overlap with) myths; but in contrast to myths, they are usually not considered “sacred”, and are mostly concerned with the human sphere, not gods or cosmology. They frequently are concerned with the origins of a particular people, settlement, custom or technology; this type of legend is also called "founding legend".
Besides explaining the origins of human institutions, another frequent function of legends is teaching morals -- as a rule of thumb, legends say a lot about the values of the society or social group where they are passed down.
And finally, they may be told to preserve and pass on (supposedly) historical knowledge, and/or simply for entertainment.
Independently from their functions, legends can be grouped in distinct genres -- mostly the following three:
Heroic Legend: Stories about ancient heroes and their awesome deeds. These are mostly martial in nature and include, but are not limited to, monster-slaying and acts of war. Heroic legends praise warrior virtues like badassery, courage, and fealty. As in most aristocratic societies the aristocracy identifies itself as a warrior elite, heroes of heroic legend are, with few exceptions, of noble blood. Heroic legends may (but don't have to) be tied to a specific mythology; if they do, the distinguishing line to myths (as mentioned above) can be blurry, as some heroes are demi-gods and thus, part human and part divine.
Religious Legend: This was the original sense of the word “legend”. Legendae (which means, not very specific, “things you should read”) were stories about Christian Saints (mostly revolving around miracles), or non-biblical traditions about biblical characters. A book that contained these was a legendarium. But religious legend is not limited to Christianity; the concept of "holy men" and women, and stories surrounding them, exist in virtually all major religions [Compare, for example, the traditions attached to boddhisattvas and arhats in Buddhism, mahatmas in Hinduism, walis in Islam, and Tzadikim in Judaism.] Religious legends extol religious devotion, piety, and whatever behavior is endorsed as exemplary by the religion at hand. -- The genre of Christian Saints’ Legends, with its focus on miracles, was much ridiculed by Protestants after the Reformation, which is when the word “legend” acquired its present-day flavor of “bullshit story”.
Folk Legend. More or less a diverse rest category for legends that exist mostly in oral form. Can overlap with the first two groups. Many folk legends are Ghost Stories; others tell of memorable Folk Heroes. Urban Legends, a.k.a. contemporary legends, may be considered the modern day's folk legends.
When a writer makes up artificial legends from scratch, whether to flesh out a fictional setting or the background of a story, or as a purpose in itself, that is a subgenre of Mythopoeia.
Examples of legends, or works treating legend:
- Classical (ancient Greek and Roman)
- The Aeneid
- The Iliad
- The Odyssey
- The lost works of the Trojan Cycle.
- Many works of Ancient Greek tragedy:
- Oedipus The King
- Oedipus At Colonus
- The Oresteia trilogy:
- The Libation Bearers
- The Progeny
- The Women Of Trachis
- Mesopotamia (Sumerian/Babylonian/Akkadian)
- The Icelandic Legendary Sagas, such as:
- Ragnar Lodbrok And His Sons
- The Saga Of The Volsungs
- The Saga Of Hrolf Kraki
- Russian & Ukrainian
The byliny, heroic lays that often feature the bogatyrs (old times heroes)
King Arthur was a Welsh hero before he morphed into the Non Action Guy known from many a Chivalric Romance.
The Golden Legend -- Jacob de Voragine's definitive legendarium of the Christian Middle Ages.
The Life Of Milarepa
The Robin Hood stories
The legend of Faust
"The Pied Piper Of Hamelin"
"The White Witch Of Rose Hall"
The legend of William Tell
While Davy Crockett was a real person, many of the stories around him are legends.
Johnny Appleseed: Like Davy Crockett, a real person surrounded by legends.