Probably the best known of the Greek Oracles are the Delphic Oracles.  The utterances of the Greek Oracles of Dodona and of Apollo at Delphi were gospel in their time, and guided the course of Greek and Roman history for several centuries.  Some complained the the prophecies were often vague, but they were occasionally quite detailed.
    When Nero visited the oracle, shortly after killing his own mother, he was told:
"Your presence here outrages the god you seek. Go back, matricide! The number 73 marks the hour of your downfall!" .
Nero, who was then 30,  thought this prophecy meant he would live to 73, so thought it a very good omen.  Nonetheless, he had the oracle and the priests put to death for daring to insult him.  Actually, the number related to Galba, who was 73 years old when he succeeded Nero in 68 AD, 14 years after the prophecy was given. 

    Another group of ancient prophecies known as the Sibylline Oracles or Sibyllae are attributed to divinely inspired seeresses who lived in the Greek colonies in the 8th century BC.  The Sibylline Oracles (1:381-388) include this prediction of the birth of Christ:

"And then the child of the great God to men
Shall come incarnate, being fashioned like
The mortals on the earth. And he shall bear
Four vowels, and the consonants in Him
Are twice told; and the whole sum I name:
For eight ones, and as many tens to these,
And yet eight hundred will the name reveal
To men who are given up to unbelief."

The numbers equate to the Greek spelling of Jesus (IESOUS).  8 ones, 8 tens and 800.  In numerology, eight is the number of enlightenment.

The Tiburtine Sibyl, composed ca. 500 AD, includes a description of the legendary Final Emperor, who will be succeeded by the Antichrist:

"At that time the Prince of Iniquity who will be called Antichrist will arise from the tribe of Dan. He will be the Son of Perdition, the head of pride, the master of error, the fulness of malice who will overturn the world and do wonders and great signs through dissimulation. He will delude many by magic art so that fire will seem to come down from heaven. The years will be shortened like months, the months like weeks, the weeks like days, the days like hours, and an hour like a moment. The unclean nations that Alexander, the Indian king, shut up will arise from the North. These are the 22 realms whose number is like the sand of the sea. When the king of the Romans hears of this he will call his army together and vanquish and utterly destroy them. After this he will come to Jerusalem, and having put off the diadem from his head and laid aside the whole imperial garb, he will hand over the empire of the Christians to God the Father and to Jesus Christ His Son. When the Roman Empire shall have ceased, then the Antichrist will be openly revealed and will sit in the House of the Lord in Jerusalem. While he is reigning, two very famous men, Elijah and Enoch, will go forth to announce the coming of the Lord. Antichrist will kill them and after three days they will be raised up by the Lord. Then there will be a great persecution, such as has not been before nor shall be thereafter. The Lord will shorten those days for the sake of the elect, and the Antichrist will be slain by the power of God through Michael the Archangel on the Mount of Olives"

And from the twelvth century,  this Catholic Sibyl's view of apocalypse:

"...The Last Judgment will follow the Abomination. Signs will precede. There will be four kinds of unusual color in the elements and a change in the course in the heavenly bodies. There will be a celestial sign in that the air will appear at times yellow, at times pitch-black, now green, now clear red. Apollo will be split, now in ten, now in four, now in two parts; the moon will run together with the sun. Those dwelling on the earth will be struck with fear when they see the stars all bloody. At the same time the earth will well up in different places, and there will be a fearful sign of commotion. There will be collision of kingdoms, seizure of thrones, earthquakes, and famines...The Last Judgment will be imminent; the signs will precede it. The sun will be frequently eclipsing and stretching out in vast fashion will destroy...Then the heavens will be opened in four parts, there will be thunder, and the inhabitants of the earth will hear the threats of Judgment...Then all the kings and princes will appear and behold the Lamb who pays back all men uupon his throne of terror. No discrimination of wealthy or poor will take place there, but only the weighing of merits...He will judge the good and evil to lift the former on high and allow hell to swallow the latter to the fate of the demons. This is the end of the book of the Erythraean Sibyl of Babylon.

"And then will God speak with a mighty voice
To all rude people of an empty mind;
And judgments from the mighty God shall come
Upon them, and they shall be destroyed
By an immortal hand. And fiery swords
Shall fall from heaven on earth, and mighty lights
Shall come down flaming in the midst of men.
And mother earth shall be tossed in those days
By an immortal hand...
But one vast friendship and one mode of life
Will be with glad people, and all things
Will common be, and equal light of life.
And wickedness from earth in the vast sea
Shall sink away. And then the harvest-time
of Mortals is near. Strong necessity
Is laid upon these things to be fulfilled.
Nor then will any other traveler say,
Recalling, that men's perishable race
Shall ever cease. And then o'er all the earth
A holy nation will the sceptre hold
Unto all ages with their mighty sires..."
(I added the emphasis on the last line)