The interesting thing about John the Baptist is that he seems to fit the description of the two witnesses fairly well, although not quite enough to draw a definitive conclusion. Maybe JtB was a type?
Here’s what I have on JtB and the two witnesses if you’re interested …
Matthew 11:14 JtB is called Elias but in John 1:21 JtB answers “no” when asked if he is Elias. In some kind of way JtB is a single person that represents 2 people, himself and Elijah.
Revelation 11:3 they are clothed in sackcloth. Mark 1:6 JtB was clothed with camel’s hair.
Revelation 11:7 when their testimony is finished the beast makes war, overcomes them, and kills them. Mathew 14:3 Herod puts JtB in prison (war), Matthew 11:2-3 JtB questions if Jesus is the Christ (overcome), and Matthew 14:10 JtB is beheaded (killed).
Revelation 11:9-10 their dead bodies are in the street for 3 ½ days and they that dwell on the earth rejoice, make merry, and send gifts. From Mark 6:29 it is possible that JtB’s body was in the street for 3 ½ days because it was only after JtB’s disciples heard of his beheading that they came and got his body; also JtB was beheaded during Herod’s birthday party which could be what making merry and sending gifts is referring to.
Revelation 11:11 after 3 ½ days the Spirit of life enters into them and they stand on their feet. In Matthew 27:52-53 after His resurrection (3 ½ days?) the graves are opened and the bodies of the saints arose. It is possible that JtB was one of the saints that arose at that time.
We know without a doubt who two of the four witnesses are because Revelation tells us who the "two candlesticks" represent. John the Baptist, a disciple of Christ would certainly be counted as one of the fellow servants among Jews of faith.
Revelation 1:20 (KJV) The mystery of the seven stars which thou sawest in my right hand, and the seven golden candlesticks. The seven stars are the angels of the seven churches: and the seven candlesticks which thou sawest are the seven churches.
Revelation 11:3-4 (KJV) And I will give power unto my two witnesses, and they shall prophesy a thousand two hundred and threescore days, clothed in sackcloth. These are the two olive trees, and the two candlesticks standing before the God of the earth.
I find it interesting that the two candlesticks prophesy a thousand two hundred and threescore days. That's the same amount of time given in Rev 12 when the woman (Israel of Old) after the birth of Christ and the war that took place in heaven fled into the wilderness to a place prepared for her by God.
Revelation 12:5-6 (KJV) And she brought forth a man child, who was to rule all nations with a rod of iron: and her child was caught up unto God, and to his throne. And the woman fled into the wilderness, where she hath a place prepared of God, that they should feed her there a thousand two hundred and threescore days.