In narrative theory, actant is a term from the actantial model of semiotic analysis of narratives. The term also has uses in linguistics, sociology, computer programming theory, and astrology.
Algirdas Julien Greimas (1917–1992), 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 (opponent of hero), object (of quest), helper (of hero) and sender (who initiates the quest)." 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 (or way of concern) 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.
[Linguistically], Actants have a kind of phonemic rather than a phonetic role: they operate on the level of function, rather than content. That is, an actant may embody itself in a particular character (termed an acteur) or it may reside in the function of more than one character in respect of their common role in the story's underlying 'oppositional' structure. In short, the deep structure of the narrative generates and defines its actants at a level beyond that of the story's surface content.