All instances of the word antichrist (all four of them) occur in the epistles of John (who may or may not have been St John the Devine). If you take the trouble to read them you will find that he is refering to people that were then living, and events that were ongoing at the time of writing (IE in the first century AD). The word antichrist does not appear in The Book of Revelation and is not - anywhere in the Bible - associated with any prophecy or end time scenario. If you want a name to associate with this title then try Simon Magus. There were other claimants to the title of Messiah (antichrists/false prophets) around during this period but their names haven't come down to us.
The question you should be asking is, 'Why do people insist on associating The Antichrist (John uses the word as an adjective by the way)with Armageddon, when there is absolutely no such association made in the Bible?'.