Who is Emmanuel Goldstein?

Emmanuel Goldstein is considered Big Brother’s most prominent enemy, who is a figurehead for the opposition and is used as a scapegoat by the Party. According to the Party, Goldstein is the leader of an underground anti-government organization known as the Brotherhood and wrote a book that explains how the authoritarian regime retains its power and control. The Party uses Emmanuel Goldstein to cultivate a hysterical atmosphere and displays his image during the daily Two Minutes Hate period. Emmanuel Goldstein is an enigmatic figure, whose whereabouts remain unknown and is dedicated to the demise of the Party and Big Brother. Fittingly, the Party blames its mistakes and miscalculations on Emmanuel Goldstein and portrays him as the ultimate villain.
Whether or not Goldstein actually exists remains unclear, but the Party does use his image and identity to strike fear into the hearts of Party members. Winston Smith, who is a political dissident, is attracted to Goldstein’s anti-government rhetoric and actually attempts to join the Brotherhood. Overall, Emmanuel Goldstein is the figurehead of the Party’s opposition and is depicted as Big Brother’s most prominent enemy.

Emmanuel Goldstein is a supposed opposition figure to Big Brother and the leading enemy of the state. O'Brien tells Winston and Julia that he is also head of a subversive underground organization called The Brotherhood, which is determined to overthrow the Party. Goldstein is said to be a great intellectual and to have written a number of books that set out, in great detail, how the Party may be defeated.
No one is absolutely certain that Emmanuel Goldstein even exists. As for The Brotherhood, it is almost certainly wholly fictitious as O'Brien is not, as he claims, an enemy of the Party, but a high-ranking cadre who is going to destroy Winston and Julia. The likelihood is that Goldstein does not really exist; he is a creation of the Party, a hate figure used as a convenient scapegoat for the the regime's failures. Inventing an oppositional figure also allows the Party to flush out potential subversives who may be inspired by his liberating message. Though deeply cynical, this is a successful counter-revolutionary strategy, one that lures Winston and Julia into a deadly trap.