“Anyone who recounts a narrative. In fiction the term is used for the ostensible author or teller of a story. In fiction presented in the first person, the ‘I’ who tells the story is the narrator; the narrator may be in any of various relations to the events described, ranging from being their center (the protagonist) through various degrees of importance (minor characters) to being merely a witness. In fiction told from an omniscient point of view, the author acts self-consciously as narrator, recounting the story and freely commenting on it. A narrator is always present, at least by implication, in any work, even a story in which a self-effacing author relates events with apparent objectivity. A narrator may be reliable or unreliable. If the narrator is reliable, the reader accepts without serious question the statements of fact and judgment. If the narrator is unreliable, the reader questions or seeks to qualify the statements of fact and judgment” (Source: Harmon & Holman, 337).
Also see: point of view.