In Greek the word is G500 ἀντίχριστος antichristos used in Total KJV Occurrences: 5 antichrist, 4.  in these scriptures 1Jo 2:18, 1Jo 2:22, 1Jo 4:3, 2Jo 1:7 antichrists, 1 1Jo 2:18.  Antichristos an-tee'-khris-tos From G473 and G5547; an opponent of the Messiah: - antichrist.  This is not a comprehensive answer; but a short thought.  The anti Christ (one against Christ) is not an individual person, especially in a certain time period.   A human's average adult life span is 50 years or so and period in power could be less. Nor is it a local or global power for a limited period of human existence. Gen 3:15 And I will put enmity between thee and the woman, and between thy seed and her seed; it shall bruise thy head, and thou shalt bruise his heel. There has been the spirit of the one against the Messiah (Christ) from creation.

This spirit operated throughout human and biblical history manifesting itself in human form of various persons who were anti God / Christ. Pharaoh and Herod for example tried to nullify the prophecy of Christ's birth by trying to killing all babes. 

There are many anti christ, deceivers of the truth of God. 2Jo 1:7 For many deceivers are entered into the world, who confess not that Jesus Christ is come in the flesh. This is a deceiver and an antichrist. Note the scripture does not say "the" anti christ. 1Jo 2:22 Who is a liar but he that denieth that Jesus is the Christ? He is antichrist, that denieth the Father and the Son. i.e anyone of many and this denial may not be the ONLY mark of an anti christ, simply the one being referred to in this verse. Infact SOME OF the Jews could fit into this criteria (not the Messianic). Though it is possible a certain one of many is referred to in 1Jo 2:18 Little children, it is the last time: and as ye have heard that antichrist shall come, even now are there many antichrists; whereby we know that it is the last time. 1Jo 4:3 And every spirit that confesseth not that Jesus Christ is come in the flesh is not of God: and this is that spirit of antichrist, whereof ye have heard that it should come; and even now already is it in the world. The Pope nor Catholic church were in the world at this time; but centuries later.

As the saying goes, like father, like son. Joh 8:44 Ye are of your father the devil, and the lusts of your father ye will do. He was a murderer from the beginning, and abode not in the truth, because there is no truth in him. When he speaketh a lie, he speaketh of his own: for he is a liar, and the father of it. So murderers, liars and those who do not abode in YAH's WAYs are liars and of the devil whether from the beginning, middle or at end of time. These can be individuals, local or global agencies anti God / Christ.

The Protestants (reformers) had a gripe against the corruption of the Catholic church. Seeing it as anti scripture. Thus THEY with their individual reading of the bible marked the Church and or its Pope leader as the anti christ. Since then that interpretaion has been passed down to subsequent protestors. It may now be taking a turn. The Protestants may be right for this generation, time will tell. But it does not cancel out the possibility of previous anti christ in previous generations. There was religious corruption through the bible. False scales, Eli's sons, using temple ground to sell sacrificial animals, paying for cleansing etc. Not necessarily the sign of anti christ; but greed.

Lastly, and without going into detail as it is a big historical topic, the title "Christ" existed long before the birth of whom we call Jesus and is taken from a pagan religion. So when we use the phrase anti Christ we are thinking of anti God. The 4 scriptures quoted above are the only ones using the word antichrist in the KJV. It is neither used in Daniel or Revelations and we may simply be making connections, inherited or otherwise that should not be there. There are different powers in the world. Political, economic and or spiritual. One may not necessarily be linked to the other. At present I believe the Bible is concerned with spiritual powers and may only mention the other two when they relate to spiritual outcomes of God's people. I read Rev 8,9,13,14 and did not see any reference to “antichrist”. 8 & 9 talks of earth’s punishment through outpouring of say, broken seals. 13 of the beast and 14 of Jesus and his people. I know teachings are that antichrist, beast and Revelation’s go together; but do they? Where is the scriptural connection rather than an imposed one?

When we saw the beasts of Daniel they related to upcoming empires. Earthly historic rulers. Could beast of Revelation not be same? Simply a future last ruler with world domination aspirations (albeit spiritual maybe)? Though I have inherited the same theology as most of you, on reflection, I presently cannot see any direct scriptural connection between an antichrist and a beast, last day events or Revelations 8,9,13,14 etc?

The big question is who were and are God’s people? At the time of Gen 3:15 it was God created Adam and Eve. After the flood it became Noah. Subsequently it became Abraham and his descendants who God separated to be a peculiar people unto Him. The promise of the Christ was to them and Jesus Himself confirmed He came to Israel. God speaking through His prophets spoke to Israel and depicted their journey from the past to the last days. Along the way they were to draw the ungodly back to Him by being a light unto them.

The protestants (ignorant of their ancient roots), coming out of what they were taught to be “The Church, God’s representative on earth” saw that body and head (Pope) as anti scripture and thus anti Christ and concluded them to be “the” antichrist. Little did they know that the body (Catholic Church) was not the original church of the apostles, Jerusalem nor representative of Israel. It was a body coming out of a body from which they came! There are other bodies (religions) which are anti God / Christ. All tentacles of satn the father of antichrists. To identify these individual tentacles we may need to look beyond that of our Protestant theology makers. Back to who was and is against God and His people Israel. These groups or individuals may not necessarily be the same in all eras i.e which human power(s) does satn use at what time.
It is my present conclusion, to seek “the” antichrist of a certain time era (if it can be restricted to one) we look to the head, satn not the individual tentacles though one of those tentacles may raise its head above others or unite with the, or some of the others at the end of God’s prophetic times, Armageddon.
As individuals, the anti-Christ with whom we should be concerned are those who seek to separate us from God and His son. Whether they be individuals we call friends, organizations or monarchs. We should oppose all such efforts, policies etc. Not only when it affects us; but also others or the directives and commandments of God. We should not allow the divide and conquer ploy of satn when he singles out others as one day we may be the ones singled out. Deuteronomy 13:1-16 and Mat 10:37 He that loveth father or mother more than me is not worthy of me: and he that loveth son or daughter more than me is not worthy of me.