The Antichrist, also known as the Beast or the Prince of Darkness, is the child of Satan (or, in the case of Damien Thorn II or Alexander York, the grandchild of Satan), and the archenemy of Jesus Christ. He is destined to rise to political power and cause war, corruption, and chaos on Earth during Armageddon, before being defeated by Christ.
The birth of the Antichrist (or at least the original Antichrist, Damien Thorn), is signaled by numerous events: the Jews returning to Israel, a comet taking the shape of a bright star over the continent where the Antichrist was born (similar to how the Star of Bethlehem formed when Jesus was born and during his Second Coming), several man-made and natural disasters, and the Treaty of Rome.
Also, the time of Damien's birth corresponded to the number 666 (the Number of the Beast): he is born on the sixth hour of the sixth day of the sixth month. The Antichrist's birth also always appears to be unholy in some way: in The Omen, Damien was born of a jackal; in Omen IV: Armageddon 2000, Damien II was born through the rectum; and in Omen IV: The Awakening, Alexander was a Vanishing twin who was born through Surrogacy.
The Antichrist bears a birthmark somewhere on his body, which is shaped like a sequence of three sixes in a triangle-shaped design. Damien's 666 birthmark was on his scalp, under his hair, while Alexander's birthmark was directly on the palm of his hand.
The Antichrist is destined to rise to political power, to use his powerful position in the world of politics to cause sin and corruption among humanity, and to bring war and chaos to the Earth. This will continue until the Antichrist is defeated during Christ's Second Coming.
The Antichrist is always evil. After the Antichrist discovers who he is, he may be horrified at first (as shown in Damien - Omen II), but will eventually embrace his destiny and attempt to avenge Satan's exile from Heaven by starting Armageddon and attempting to destroy the Christ. The Antichrist apparently also fears holy objects and hallowed ground, as Damien deeply feared churches when he was a child in The Omen.
While the Antichrist will not be consciously aware of who he is until he discovers it for himself (as shown in Damien - Omen II), it does appear that he will be subconsciously aware of his powers at the least. According to Carl Bugenhagen, the Antichrist is born evil, and is "evil incarnate."
Powers and Abilities
The original Antichrist, Damien Thorn, could unnerve people or cause them to see horrific visions simply by staring them in the eye, as shown in The Omen and Damien - Omen II. In Damien - Omen II and The Final Conflict, he could also cause accident-like events to happen, such as machinery breaking down and/or not working, fires starting, objects moving, and aneurysms in people's blood vessels.
In The Final Conflict, Damien was also shown to be able control animals such as dogs and horses, and make them do his bidding, and could make people hallucinate another person as someone else. It was made apparent in The Omen that the Antichrist is also immune to all mortal ailments, both severe and minor; including colds, coughs, mumps, chicken pox, and chemical poisoning.
The Antichrist can also sense when a very powerful holy event happens, as Damien reacted with pain and discomfort when the second Star of Bethlehem formed in The Final Conflict. It was also shown in Damien - Omen II that the Antichrist subconsciously knows the date of virtually every historical event known.
Recognizing the Antichrist
Some people can subconsciously recognize the Antichrist. For example, in Damien - Omen II, Marion believed that Damien was dangerous and a bad influence, and in The Omen, Katherine Thorn had several nightmares of Damien which caused her subconscious to recognize that Damien was evil and was not her biological son.
Animals can also recognize the Antichrist, as in The Omen, animals such as giraffes were shown to flee in fear upon noticing Damien, and primates such as baboons, lemurs, and gorillas would react with fear and aggression at the sight of him. In The Omen (novelization), Damien also had no fingerprints.
Damien possessed a great fear of churches when he was a child in The Omen. Also, the Daggers of Megiddo are the only things that can harm the Antichrist. If all seven Daggers are stabbed in the Antichrist's chest in a sequence that forms the cross, and the Antichrist is stabbed on hallowed ground and dies on a church altar, then the Antichrist's physical body will die and his spiritual energy will be extinguished; permanently destroying him. However, as shown in Omen IV: Armageddon 2000, if the ritual is not carried out this specific way, while the Antichrist's body may die, his soul will survive and live on.
In Christian Lore
The Antichrist is described in the Book of Revelation as the archenemy of Christianity, and mankind's final opponent before man's liberation by Jesus Christ. During the Apocalypse, the Antichrist will tempt mankind and lead nations to war, and cause sin and corruption to rise.