 The word antihero has actually been around since 1714, but the use of an antihero as the main character of fiction has become more widespread only in recent years. (Merriam-Webster Online)
One might say that moral ambiguity plays a key role in the development of the antihero. In essence, there can be no antihero unless there is first a world of unclear morals in which the antihero stumbles about. The antihero is defined by the way in which he interacts with the world around him—traditionally an interaction that is unusual at best. In the essay entitled “Animal Rationis Capax,” Kathleen Williams seeks to explain how one of the main purposes of Gulliver's Travels is to sum up "the nature of man and...his proper behavior in a difficult world."(Bloom 37) Gulliver remains a hero throughout most of the book, but becomes an indisputable antihero when he returns from his travels in foreign lands. Having learned from a species of intelligent talking horses that the way humans do things is largely uncivilized, Gulliver returns to the world of men to find that he sees everything he knew in a much different light. Suddenly he is a moral compass of sorts to his fellow men, being the only one of them who is aware of the superior way of living that  was taught to him by the horse people.
Perhaps one of the great antiheroes of literature is Holden Caulfield in Catcher in the Rye. In this novel J.D. Salinger is not so much concerned with morals, but with whether or not one should believe in these morals. As a review by Virgilia Peterson in A Catcher Casebook puts it, Holden is at heart a good kid, but is also very much a believable character, with inherent character flaws. (Marsden 3) In the foreword of A Catcher Casebook, Holden is called the “epitome of the real American.” (Marsden foreword) Unlike all the adults and children around him who walk around in a conformist state—seemingly anesthetized to the way things are—Holden is honest with himself, and admits that a lot of things that happen in the world today do not make very much sense to him:
“The cause of …[Holden’s] alienation is placed at the doors of schools, churches, business houses, government bureaus. They are charged with thwarting human aspirations, frustrating conscience, outraging sensitivity…The young man is full of love and courage, innocent and good, a wise sheep forced into lone wolf’s clothing. He pierces the shams and deceits and vulgarity of a phony society which botches things so terribly that at last Holden has no escape except a mental institution.” (Marsden, 35)
Holden looks authority in the eye and spits right in its face. He senses that something is very wrong with how the world works today, yet feels helpless to do anything about it. Unable to articulate himself in a responsible manner, he turns to delinquency as a means of self expression. 
