A persona is a fictional character that plays out scenarios. The fundamental contrast between a persona and an actor in a conventional use case is that the former is discovered through ethnographic research and is intended to represent a plausible person who exists for more reasons than to interact with the product. This affords personae to be both more robust and more rigid than conventional use case actors, circumventing Alan Cooper's elastic user problem.
A persona may also refer to the actual document that contains this character sketch.