Who is the antichrist.?

In short, because this topic is broad, he is the opposite of Jesus Christ. He will come to rule the world and lead it into the Apocalypse. He will be the one ruler of the world for seven years. In the middle of his reign, he will be killed. He will come back to life, but will be possessed by Satan. He will say he is god after this. Hence the reason he is called the Antichrist: he came back from the dead and is controlled by Satan. At the end of his reign, he will lead an army against Israel. He will gather them at Meggido, or as we say it Armageddon, and that will be the final battle on earth.