The most likely candidates for the end times two witness scenario are Enoch and Elijah, neither of whom died a physical death, but will be killed after their 42 month testimony. They are the only humans we read of who were not laid to rest with their ancestors.
Genesis 5:21 ~
When Enoch had lived 65 years, he begot Methuselah. After the birth of Methuselah, Enoch walked with Yah 300 years; and he begot sons and daughters. All the days of Enoch came to 365 years. Enoch walked with Yahweh, then he was no more, for Yah took him.
II Kings 2:11 ~
As they kept on walking and talking (Elijah and Elisha), a fiery chariot with fiery horses suddenly appeared and separated them, and Elijah went up to heaven in a whirlwind.
The Two Witnesses are described as "the two olive trees and the two menorahs which stand before Master Yahweh. They have the power to stop the rain, to turn water to blood, and to produce all plagues as often as they please. They can send fire out of their mouths and consume who ever attacks them." And they will be giving testimony for 3-1/2 years = 42 months = 1260 days. Then the Beast that came up from the abyss will make war with them and overcome them. They will leave their bodies in the street for 3-1/2 days while folks celebrate their death. And then Yah will call them up - in that same hour an earthquake destroys part of the city and kills 7,000 people - the rest gave glory to Elohim.
I do not believe that Yah would use someone already dead to fulfill this prophecy as they must die and be 'resurrected' at that time. Y'shua is our example of one being born, tasted death and was resurrected as the first fruits of the dead. He now sits at the right hand of his Father. Lazarus died and was brought back to life by Y'shua. Enoch and Elijah are not dead but were changed in form and in place. Yah took them because He had a big plan for them to fulfill during the final 3-1/2 years of life as we know it.
1 Kings 17 ~ Elijah the Tishbite who lives in Gilead, said to Ahab, "As Yahweh Lives, the Elohim of Israel whom I serve, there will be no dew or rain except at my bidding."
Here we read that Elijah has the power to hold back the rain as he sees fits. This is one of the many powers the two end times witnesses have.
And here is the clincher! We read at the end of Malachi:
I will send the prophet Elijah to you before the coming of the awesome, fearful day of Yahweh. He shall reconcile parents with children and children with their parents, so that, when I come, I do not strike the whole land with utter destruction.
This sounds akin to the command to paint the doorposts and lintels with the blood of the lamb so that the Messenger of death would pass over those places. Same goes for us today who accept the shed blood of Y'shua to save us from death and spending eternity in Fire Lake. Elijah, by his testimony, will cause many to cease being enemies with one another and stop rebelling against Yah; the rest will be destroyed with those final cups of wrath.
Hebrews 11:5 ~
By faith Enoch was translated and did not taste death; and he was not found because Elohim had translated him; for, before he translated him, there was testimony of him that he pleased Elohim. But without faith, a man cannot please Elohim.
Translated defined: to bear, remove, or change from one place, state, form, or appearance to another; to convey to heaven or to a nontemporal condition without death
Neither Enoch nor Elijah have died.
And to note, we who are His Set Apart believers will be changed when that time comes to be gathered together in the clouds at the return of Y'shua. We will be changed in form, being made incorruptible. We shall be incapable of corruption such as no longer subject to decay or dissolution. When we enter the promised land, the earthly kingdom of Y'shua the Anointed One, our 'bodies' will be like that of the Messengers (angels):
Mark 12:25 ~
For when they rise from the dead, they do not marry women nor are women given in marriage to men. Rather, they are like the Messengers who are in heaven. (aka: incorruptible spiritual beings = translated from one form to another.)
If we read from the book of Enoch we learn that he did achieve high standing in the heavenlies to the point I sometimes think he replaced the job opening left by Satan.
Please Note: I recommend one be fully in the Word of Elohim via the study of Scriptures before using other writings such as Enoch and Jasher so that one can discern that which lines up with Scriptures. I do not substitute anything for the Word of our Creator yet find these sources help describe possible scenarios which are only alluded to in Scriptures. YHWH is our final word on all things. And we know, if everything that He did and everything that Y'shua did was written down the earth wouldn't be big enough to store all those books 😉