The 2 witnesses! These 2 are killed after the 1st 3 1/2 year period which begins the GREAT TRIBULATION
11:3 And I will give power unto my two witnesses, and they shall prophesy a thousand two hundred and threescore days, clothed in sackcloth.
11:4 These are the two olive trees, and the two candlesticks standing before the God of the earth.
11:5 And if any man will hurt them, fire proceedeth out of their mouth, and devoureth their enemies: and if any man will hurt them, he must in this manner be killed.
11:6 These have power to shut heaven, that it rain not in the days of their prophecy: and have power over waters to turn them to blood, and to smite the earth with all plagues, as often as they will.
117 And when they shall have finished their testimony, the beast that ascendeth out of the bottomless pit shall make war against them, and shall overcome them, and kill them.
AND One of the Two Witnesses will be John the revelator?
10:7 But in the days of the voice of the seventh angel, when he shall begin to sound, the mystery of God should be finished, as he hath declared to his servants the prophets
10:8 And the voice which I heard from heaven spake unto me again, and said, Go and take the little book which is open in the hand of the angel which standeth upon the sea and upon the earth.
10:9 And I went unto the angel, and said unto him, Give me the little book. And he said unto me, Take it, and eat it up; and it shall make thy belly bitter, but it shall be in thy mouth sweet as honey.
10:10 And I took the little book out of the angel's hand, and ate it up; and it was in my mouth sweet as honey: and as soon as I had eaten it, my belly was bitter.
10:11 And he said unto me, Thou must prophesy again before many peoples, and nations, and tongues, and kings.
Some have said that this promise, "Thou must prophesy again before many peoples, and nations, and tongues, and kings" (10:11), has already been fulfilled by the spread of the New Testament Scriptures, including the Gospel of John, the Epistles of John, and the Revelation. Certainly, the promise has been fulfilled in some measure. But, the fact that the Apostle John was shown the contents of the Little Book and was told not to divulge it to the readers of this Apocalypse (10:4), indicates that John will be back at a future time during the Tribulation to make plain to all exactly what he was shown. Commentary on.Revelation Chapter 10
The 2 witnesses will either be {Elijah and Enoch}because they presently reside in heaven in their flesh, bones, and blood bodies or {John and Daniel}because of what rev 10:11 says and that they both heard the book that was sealed
(Dan 12:4) But thou, O Daniel, shut up the words, and seal the book, even to the time of the end: many shall run to and fro, and knowledge shall be increased.
(Dan 12:9) And he said, Go thy way, Daniel: for the words are closed up and sealed till the time of the end.
(Dan 12:13) But go thou thy way till the end be: for thou shalt rest, and stand in thy lot at the end of the days