First there has been many Anti-Christ in history. There are Anti-Christ walking the Earth today.

In 1 John 2:18–19, we read, “Children, it is the last hour; and as you have heard that antichrist is coming, so now many antichrists have come; therefore we know that it is the last hour. They went out from us, but they were not of us; for if they had been of us, they would have continued with us; but they went out, that it might be plain that they all are not of us.”

Nero was an Anti-Christ. So were other powerful political douches like Napoleon, Hitler, Stalin, Franco, Mao, Xi, Putin, the Kims, and the socialist leaders of Cuba and Venezuela. Even smaller scale Anti-Christ such as Charles Manson who led his family to anti Christian values of murder and hate.

Now I get that you are referring to THE Endtimes Anti-Christ, but noted above is that the frequency of “smaller” Anti-Christs is actually a sign of the End Times!

In 1 John 2:22–23, we read, “Who is the liar but he who denies that Jesus is the Christ? This is the antichrist, he who denies the Father and the Son. No one who denies the Son has the Father. He who confesses the Son has the Father also.”

1 John 4:1–6 gives practical tests for discerning which spirits bearing revelation are from God and which are not. In John 4:3, we read that “every spirit which does not confess Jesus is not of God. This is the spirit of Antichrist, of which you heard that it was coming, and now it is in the world already.”

Finally, in 2 John 7, we read, “For many deceivers have gone out into the world, men who will not acknowledge the coming of Jesus Christ in the flesh; such a one is the deceiver and the antichrist.”

The beast from the sea that John speaks of in Revelation is best understood in its initial, literal fulfillment as one of the early Roman emperors (cf. Catechism of the Catholic Church 2113 on the past fulfillment of this prophecy). Yet, there are often multiple fulfillments of a single prophecy, and the beast may also point forward to an individual at the end of time who will be very much like the early Roman emperors.

Such an individual is easy to identify with Paul’s “man of lawlessness,” for he appears to be a still-future individual who does things like the Roman emperors. Paul states that he will one day manifest himself in the temple of God—which to a first-century Jew would mean the Jewish temple in Jerusalem—and demand to be worshiped as a god. But it is not a hindrance to identifying the future, individual Antichrist with the future man of lawlessness or a future fulfillment of the beast from the sea, since future emperor-like individuals may have a personal, familial, or national Christian background.

All of the above cut and pasted from Jimmy Akin’s catholic,com.