al-Dajjal (Arabic: الدّجّال, al-dajjāl) (“The Deceiver/impostor”), also known as the false Messiah (see also: Antichrist) is an evil figure in Islamic eschatology, who will appear before Yawm al-Qiyamah (The Day of Resurrection, Judgement Day).
“Dajjal” is a common Arabic word, used in the sense of “false prophet”. But “Al-Dajjal”, with the definite article, refers to “The Impostor”, a specific end-of time deceiver. It is worthy to note that the term Al-Masih Ad-Dajjal (Arabic for “The False Messiah”) is a literal translation of the Syriac term “Meshiha Deghala”, which had been in the common vocabulary of the Middle East and adapted into the Arabic language 400 years prior to the Qur’an via the Peshitta (which uses that term instead of the Greek “antichristos”)
The beleif is based around the events prior to the day of judgement around the Second Coming of christ, when Dajjal shall gather an army of those he has deceived and lead them in a war against Jesus, who shall be accompanied by an army of the righteous.
Islam’s description of the “Dajjal”
- Once Allah’s Apostle stood amongst the people, glorified and praised Allah as He deserved and then mentioned the Dajjal saying, “l warn you against him (i.e. the Dajjal) and there was no prophet but warned his nation against him. No doubt, Noah warned his nation against him but I tell you about him something of which no prophet told his nation before me. You should know that he is one-eyed, and Allah is not one-eyed.”
- Allah’s Apostle said, “Shall I not tell you about the Dajjal a story of which no prophet told his nation? The Dajjall is one-eyed and will bring with him what will resemble Hell and Paradise, and what he will call Paradise will be actually Hell; so I warn you (against him) as Noah warned his nation against him.” 
- ‘Abdullah reported on the authority of his father ‘Umar b. Khattab that he heard from the Messenger of Allah (may peace he upon him) say: I was sleeping when I saw myself making circuit around the Ka’bah, and I saw there a man of fair complexion with straight hair between two men. Water was flowing from his head or water was falling from his head. I said: Who is he? They answered: He is the son of Mary. Then I moved forward and cast a glance and there was a bulky man of red complexion with thick locks of hair on his head, blind of one eye as it his eye was a swollen grape. I asked: Who is he? They said: He is Dajjal. He had close resemblance with Ibn Qatan amongst men.
- John Whiteside Parsons claimed to be the Antichrist and the Dajjal.
- Dajjal, the forgotten story, by S.M. Mazari, Tangerine Editions.