The Antichrist
"The Apocalypse, or Book of Revelation, is not only the last Book of the New Testament, but its most difficult, puzzling, and terrifying. It provided challenges to medieval illustrators and was the source for a number of popular images, such as Christ in Majesty, the Adoration of the Lamb, and the Madonna of the Apocalypse and contributed to the widespread use of the Evangelists' symbols."
When the Apocalypse comes, would you know what the Antichrist would look like? Regardless of your religious beliefs (or non-belief), surely you'll agree that the apocalyptical illustrations of the medieval Beatus Apocalypse are gorgeous.
Another great find by peacay of BibliOdyssey: Link
Also, when you read the letters John wrote (especially 2 John and 3 John), you realize that there are many anti-Christs (to paraphrase, anyone who says God is anything but love is an anti-Christ).