A character was an individual, animal, or thing/object that was being presented as a person, in a narrative.
In 3074, a copy of The Doctor left behind on the Kyrian and Vaskan homeworld acknowledged that their simulation of USS Voyager's encounter with them was at least founded on reality, if not true to it, saying, "Well, the stage is certainly set, but I'll have to rewrite the characters and revise the plot a little." (VOY: "Living Witness")