God used a "mark" to literally identify Cain in Gen. 4:15 so that no one would seek vengeance for the death of Abel. But, most of the time the word "mark" was a term / idiom which meant to "take note" of certain places or certain people.
Ruth 3:4, Naomi's instructions to Ruth,
"And it shall be, when he lieth down, that thou shalt mark the place where he shall lie..." (KJV)
1 Kings 20:7,
"Then the king of Israel called all the elders of the land, and said, Mark, I pray you, and see how this man seeketh mischief:..." (KJV)
Or, in many cases it meant a target as in Job 16:12,
"I was at ease, but he hath broken me asunder: he hath also taken me by my neck, and shaken me to pieces, and set me up for his mark." (KJV)
Psa. 37:37 expresses the better meaning as it us used in Revelation.
"Mark the perfect man, and behold the upright: for the end of that man is peace." (KJV)
The sense is to take notice of the behavior of that man of peace, or to take notice of the sin against God as in Jeremiah chap. 2.
"For though thou wash thee with nitre, and take thee much soap, yet thine iniquity is marked before me, saith the Lord GOD." (KJV)
"Now I beseech you, brethren, mark them which cause divisions..." (KJV)
In Revelation, as in Ezekiel it was not a literal "mark" upon their foreheads. The Greek word is "χάραγμα" or "charagma", and is Strong's 5480 defined as a "sculpture" as in a stamp, engraving, or a sign. It was a "brand" mark that was impressed in a coin or a seal or a die-stamp.
Excerpt from Barnes' Notes on the Bible,
"Applied to people, it was used to denote some stamp or mark on the hand or elsewhere - as in the case of a servant on whose hand or arm the name of the master was impressed; or of a soldier on whom some mark was impressed denoting the company or phalanx to which he belonged. It was no uncommon thing to mark slaves or soldiers in this way; and the design was either to denote their ownership or rank, or to prevent their escaping so as not to be detected." Source: here
Having the "mark" or brand of the beast was a literary device in Revelation that represented a common practice of branding slaves with their owners "mark" or "seal". The intent in Revelation was that those who chose to follow the "beast" were branded spiritually by their behavior and worship of the beast.
As opposed to those who chose voluntarily to follow Christ. The believers / disciples of Christ were "sealed" by God who "marked" them as belonging to Him.
The mark of the beast in Revelation is a representation of those who chose to worship the "god" that was demanding such worship of all his subjects /citizens whom he ruled.... Caesar. In the first century A.D. the beast of the sea was the emperor of Rome who declared himself to be a god, and/ or the son of god.
The "sea" in Revelation was the representation of all of the heathen nations that surrounded the "earth" or the land of Judea and Palestine where the remnant of Israel lived. The beast of the land in Rev. 13:11 was the oppressive ruling authority over the Judeans, namely the Sanhedrin - the Sadducees and Pharisees.
We can find an example of that beast of the old Roman empire in any ruling authority that oppresses the people in any generation. Beasts in nature are those animals that prey upon the young and the weak. God used that term to indicate evil rulers that preyed upon the weaker people of their land.
In the Messianic prophesy of Ezekiel c. 34, God compared the wicked "shepherds" who were oppressing His people - the flock - His sheep,
" Therefore will I save my flock, and they shall no more be a prey; and I will judge between cattle and cattle." (KJV)
and then compares the evil shepherds to the wild beasts in verse 25,
"And I will make with them a covenant of peace, and will cause the evil beasts to cease out of the land:..." (KJV)
So, any ruling authority or government which does not judge righteously and which oppresses the people is in God's eyes as a wild beast preying upon and devouring the weak. We can certainly see examples of these wild beasts all around us today. But, the beast of the sea in Revelation was the old Roman empire. And, those that willingly bowed down to Caesar were marked by God just as surely as if they were literally branded.
They were certainly threatened and coerced for fear of their lives and livelihood, but they made the choice. It was a voluntary decision whether to follow Christ or to bow down to Caesar. And, we have that same choice today.
I have more scriptural evidences of the beasts of Revelation in the post "The Signs of Revelation - Part V: The Animal Symbols of the Battle" at my blog here.