Verse 15: And the kings of the earth, and the great men, and the rich men, and the chief captains, and the mighty men, and every bondman, and every free man, (Is. 2:19) hid themselves in the dens and in the rocks of the mountains…
[And the kings of the earth] The sons and daughters of Agrippa, who are thus called βασιλεῖς/kings, just as the daughters of Kings are called ἄνασσαι/ queens/ladies in the Tragedies on account of their dignity of birth; and Governors, whom the Hebrews call Kings. See Acts 4:26 (Grotius). Those that had the greatest authority among the Jews (Hammond). Others: The Emperors, Maximianus, Galerius, Maxentius, etc., who attempted to uphold the ancestral religion, and to restore the fallen interests of the Gods, by force and violence (Mede’s Works 558, Durham). Others: This ought to be extended to all the enemies of the Church from the beginning of the world, etc. (Pareus).
[And the princes, etc., καὶ οἱ μεγιστᾶνες, etc.] אַדִּירִים, in Jeremiah 14:3; Daniel 3:24; Nahum 2:5; Zechariah 11:2. Suetonius, Tacitus, Seneca, and our Mark, Mark 6:21, make use of the word μεγιστᾶνες (Grotius). And the aristocrats (or, nobles [Piscator]: Companions of the Emperors in infidelity and idolatry [Mede’s Works 558]), and the rich, and tribunes (or, chiliarchs [Menochius], Commanders of thousands, Exodus 18:21 and elsewhere [Grotius]), and mighty men (Beza, Piscator): Soldiers, Judges 5:22; Jeremiah 49:22; Lamentations 1:15 (Grotius).
[And every slave and freeman] All the classes of men, the highest, the middle, the lowest, with no distinction, will be thoroughly terrified with such great portents (Grotius). All the impious; but those especially that assisted the Kings in the persecution of the saints (Ribera).
[They hid themselves in caves and rocks of the mountains] For those are thought to be safest in an Earthquake. Seneca, What hiding place do we provide, what support…if that which protects and sustains us…which some have said is the foundation of the world, splits and totters? See Isaiah 2:19 (Grotius). This was exactly fulfilled in the Jews, who, with the City captured, hid themselves in the hollows and walls of the Temple, from which most were dragged, etc. Now, as the Temple is often called the mountain of God, so its walls are called the rocks of the mountain, etc. (Hammond). They will do the very thing that they had often compelled the pious to do, who had removed themselves for fear of tyrants, etc. (Pareus). The image here is disgraceful, both of those fleeing and hiding, and of those wearied of life because of the hopelessness of their affairs: which sort of image is in Isaiah 2:19; Hosea 10:8; Luke 23:30 (Mede’s Works 558).
And the kings, etc.: A terror shall fall upon all sorts of men, high and low; and, like men affrighted, they shall seek for themselves hiding places, where they can think themselves most secure: see Isaiah 2:19.
 Greek: καὶ οἱ βασιλεῖς τῆς γῆς, καὶ οἱ μεγιστᾶνες, καὶ οἱ πλούσιοι, καὶ οἱ χιλίαρχοι, καὶ οἱ δυνατοί, καὶ πᾶς δοῦλος καὶ πᾶς ἐλεύθερος, ἔκρυψαν ἑαυτοὺς εἰς τὰ σπήλαια καὶ εἰς τὰς πέτρας τῶν ὀρέων.  Revelation 6:15: “And the kings of the earth, and the great men (καὶ οἱ μεγιστᾶνες), and the rich men, and the chief captains, and the mighty men, and every bondman, and every free man, hid themselves in the dens and in the rocks of the mountains…”  Jeremiah 14:3: “And their nobles (וְאַדִּרֵיהֶם; καὶ οἱ μεγιστᾶνες αὐτῆς, in the Septuagint) have sent their little ones to the waters: they came to the pits, and found no water; they returned with their vessels empty; they were ashamed and confounded, and covered their heads.”  Daniel 3:24a: “Then Nebuchadnezzar the king was astonied, and rose up in haste, and spake, and said unto his counselors (לְהַדָּבְרוֹהִי; τοῖς μεγιστᾶσιν αὐτοῦ, in Theodotion)…” It appears that the Chaldean word, הַדָּבַר/counselor, is being related to הֲדַר/honor; which is a cognate to the Hebrew אָדַר, to be great.  Nahum 2:5: “He shall recount his worthies (אַדִּירָיו; οἱ μεγιστᾶνες αὐτῶν, in the Septuagint): they shall stumble in their walk; they shall make haste to the wall thereof, and the defence shall be prepared.”  Zechariah 11:2: “Howl, fir tree; for the cedar is fallen; because the mighty (אַדִּרִים; μεγιστᾶνες, in the Septuagint) are spoiled: howl, O ye oaks of Bashan; for the forest of the vintage is come down.”  Gaius Suetonius Tranquillus (c. 75- c. 130) was a Roman historian.  Mark 6:21: “And when a convenient day was come, that Herod on his birthday made a supper to his lords (μεγιστᾶσιν), high captains, and chief estates of Galilee…”  Greek: χιλίαρχοι.  Exodus 18:21: “Moreover thou shalt provide out of all the people able men, such as fear God, men of truth, hating covetousness; and place such over them, to be rulers of thousands (שָׂרֵ֤י אֲלָפִים֙; χιλιάρχους/chiliarchs, in the Septuagint), and rulers of hundreds, rulers of fifties, and rulers of tens.”  Greek: δυνατοί.  Judges 5:22: “Then were the horsehoofs broken by the means of the pransings, the pransings of their mighty ones (אַבִּירָיו; δυνατῶν αὐτοῦ, in Codex Alexandrinus).”  Seneca the Younger’s Moral Epistles (Epistulæ Morales ad Lucilium), Epistle 82, “On the Natural Fear of Death”.  For example, Isaiah 2:2, 3.