Single verse????
I posted a number of verses, in context, containing the very words of Jesus Christ which clearly identify Jesus Christ as the Alpha and Omega, the first and the last, the Almighty, the one who was dead and is now alive and the one who was, and is, and is to come and the one who is coming quickly and who is identified by John as being the Lord Jesus.
If the very words of Christ are not sufficient to show you who he is, then nothing any of us is going to say will convince you.
1 In the beginning was the Word, and the Word was with God, and the Word was God. 2 The same was in the beginning with God. 3 All things were made by him: and without him was made nothing that was made. 4 In him was life, and the life was the light of men.
14 And the Word was made flesh, and dwelt among us, (and we saw his glory, the glory as it were of the only begotten of the Father,) full of grace and truth.
-- John 1:1-4, 14