, professor of semiotics, is widely credited with producing the actantial model in 1966. This model reveals the structural roles typically performed in story telling; such as "hero, villain, object, helper and sender." Each of these roles fulfill an integral component of the story, or, narrative. Without the contribution of each actant, the story may be incomplete. Thus, an "actant" is not simply a character in a story, but an integral structural element upon which the narrative revolves. An actant can also be described as a binary opposition pairing, such as a hero paired with a villain, a dragon paired with a dragon slaying sword, a helper paired with an opponent. Actantal relationships are therefore incredibly useful in generating problems within a narrative that have to be overcome, providing contrast, or in defining an antagonistic force within the narrative. However, the same character can simultaneously have a different actant in regard to a different sequence of action, event or episode in the story. Therefore, it should be distinguished from a character's consistent role in the story like the archetype of a character. The concept of actant is important in structuralism of narratology to regard each situation as the minimum independent unit of story.
In 1969 Julia Kristeva also attempted to understand the dynamic development of the situations in narratives with Greimas's actantial model. She thought the subject and the object can exchange positions, and accordingly the supporter and the opponent can exchange positions too. Furthermore, the pair of subject and object sometimes exchanges its position with the pair of supporter and opponent. There are, however, multiple overlapping situations in narrative at a given time. To contend with the overlapping situations present in all narrative structure, she called the potential actant shifts not "change", but "transformation." This should not be confused with Greimas's own transformational model, another narratological framework.
However, these are not the types of the person in the story, but rather patterns of behavior: the same person may sometimes as one "sphere", and at other times as a different "sphere".
In linguistics
Linguist Lucien Tesnière considered the function of a verb as most important in dependency grammar and invented the term "actant", various persons that accompany a verb:
Since ancient times, astrology considered and analyzed the position of the persons concerning a situation with the symbols of the celestial objects and constellations. Georges Polti counted up the needed positions in his famousThe Thirty-Six Dramatic Situations. Étienne Souriau reduced them to only 6 positions named "dramaturgic functions" with astrological symbols:
