Who is the beast? And whose number is 666?
B. Hodge, Biblical Authority Ministries, June 16, 2020
Read Daniel 7.
The four beasts are empires as Daniel pointed out. As history unfolded, they were:
1. Babylonian Empire
2. Media-Persian Empire
3. Greek Empire
4. Roman Empire
The first beast was Babylon with which Daniel was currently familiar and living during.Then he point out that the second beast is of Media and Persia (Daniel 8:20). The third beast is Greece and the horn between the eye of that third beast was its first King and then Greece would break into four kingdoms after this king (Daniel 8:21-22). True to the prophecy, Alexander the Great conquered and rose in power to form the Grecian Empire. Due to his early death, the Greek Empire broke into four parts (1) Seleucid Asia, (2) Ptolemaic Egypt, (3) Lysimachus Thrace, and (4) Macedonia-Greece), none with power that Alexander had.
The fourth beast encompassed them all. The beast during the writing of the book of John is the Roman Empire (the fourth beast of Daniel, Daniel 7:23). Christ lived under this beast and the Jews swore allegiance to the beast over the Kings of Kings, Jesus Christ (John 19:12-15). The Empire of Rome devoured all these other kingdoms and though we know its provinces, Rome's power extended far beyond by controlling trade to India and China. Even unconquered lands like Scotland and Germany were influenced by Rome to such a degree that the Latin alphabet of Rome still dominates their lands today. Interestingly, even the Romans were familiar with the Americas about 2,000 years ago after a Roman shipwreck in Nova Scotia, Canada was discovered, among other Roman relics being found in pre-colonial archaeological digs.
So Rome is without a doubt, the beast in question. See also: Revelation 17:7-10; 13:1-7, 13:18. But individually, the head/king of the empire is also the specific beast in charge (Daniel 7:17). At the time, this is Nero, the first major Roman persecutor of the Christians after the resurrection and in vicious ways no less (more on this in a moment). Revelation 17:9-10:
"Here is the mind which has wisdom: The seven heads are seven mountains on which the woman sits." There are also seven kings. Five have fallen, one is, and the other has not yet come. And when he comes, he must continue a short time. (NKJV)
1. Julius Caesar 48 B.C. – 44 B.C. (murdered by Senators, the name Caesar is the standard name given to subsequent emperors)
2. Augustus 31 B.C. – A.D. 14
3. Tiberius A.D. 14-37
4. Caligula Gaius A.D. 37-41
5. Claudius A.D. 41-54
6. Nero (arguably led the most viscous persecution/tribulation to the church ever with Peter and Paul even being executed) A.D. 54-68
7. Galba (short reign of only 6 months) A.D. 68-69
8. Otho A.D. 69
9. Vitellius A.D. 69
10. Vespian A.D. 69-79
11. Titus A.D. 79-81
12. Domitian A.D. 81-96
Nero was the sixth emperor (five had fallen before him) and the emperor that came after him reigned only a short time. At the time of the apostles, who would wage a war against Rome (Revelation 13:4)? It would be almost ludicrous. The only one capable of war against Rome is God. And yet, there was severe persecution by Nero (Rome) and the Jews (Israel) on Christians, who are the very "sons of God" (Galatians 3:26).
Revelation 17:7-9 point out that that the beast being ridden by the harlot sits on seven hills/mountains (Remember the Jews of Jerusalem with the High Priest said to Christ Himself that they were aligned with the head of the beast, Caesar—John 19:15). Rome is the only famed city of antiquity that sits on seven hills. The Roman Empire was that beast.
Here is wisdom. Let him who has understanding calculate the number of the beast, for it is the number of a man: His number is 666. (NKJV, Revelation 13:18)
In ancient times, it was common that letters were assigned a numerical value. Some people would even go by their number such as Octavius (which means 8th) as their name. Regarding 666, Neron Caesar (Hebrew spelling and popularly attested to in archaeology) is the one specified. Jastrow’s Lexicon of the Talmud: Nrwn Qsr (Neron Caesar) = 666 (n=50; r=200, w=6, n=50, q=100, s=60, r=200) affirms this addition.
This is a human number since it pertains to a man, the head of the beast and the persona of the beast at the time. Even money bore his image that you used to buy and sell things.
Nero is the lawless one (no authority over him and he could do what he wanted) and initially was being held back (even Paul appealed to him and Nero set him free the first time, Paul’s allusion to one of his releases is in 2 Timothy 4:14-17; see also Revelation 13:2) and had Christians in his own household (Philippians 4:22) but after some time he turned on Christians even killing Paul and Peter and did unspeakable crimes against Christians when he was no longer held back.
Rome was that fourth beast and Nero, the head of the beast, is a striking fit—they were persecuting the saints terribly (Daniel 7:21-22, 7:25). But it does call for wisdom to understand.
Read Revelation 13
 The name Caesar also became the name of kings after this including variation such as Kaisers, Tsar, Cisar, Kesar, etc.)
 If someone argues that you can’t begin with Julius Caesar as the first emperor of Rome, the date is still prior to A.D. 7-0 as four emperors reigned in A.D. 69.