There are lots of dragons in the Bible. They are mentioned 40 times, not including the apocrypha, which mentions them another 11 times.
It's hard to know what to make of the Bible's dragons, but here are a few things we can say about them.
Dragons are poisonous, like the Israelite's wine.
Their [the Israelites'] wine is the poison of dragons, and the cruel venom of asps. Deuteronomy 32:33
Job is their brother.
I [Job] am a brother to dragons. Job 30:29
God broke some dragon heads in the water.
Thou didst divide the sea by thy strength: thou brakest the heads of the dragons in the waters. Psalm 74:13
Those that live in God's secret place will trample the dragon under their feet.
He that dwelleth in the secret place of the most High shall abide under the shadow of the Almighty ... The dragon shalt thou trample under feet. Psalm 91:1-13
Dragons can praise the Lord.
Praise the LORD from the earth, ye dragons, and all deeps. Psalm 148:7
Dragons live in pleasant, but somewhat messy, palaces
And the wild beasts of the islands shall cry in their desolate houses, and dragons in their pleasant palaces. Isaiah 13:22
And thorns shall come up in her palaces, nettles and brambles in the fortresses thereof: and it shall be an habitation of dragons. Isaiah 34:13
Someday God will kill the sea dragon with his sword.
In that day the LORD with his sore and great and strong sword ... he shall slay the dragon that is in the sea. Isaiah 27:1
Dragons will honor God, because he gives them water in the wilderness.
The beast of the field shall honour me, the dragons and the owls: because I give waters in the wilderness, and rivers in the desert. Isaiah 43:20
God wounded the dragon.
Awake, awake, put on strength, O arm of the LORD; awake, as in the ancient days, in the generations of old. Art thou not it that ... wounded the dragon? Isaiah 51:9
Jerusalem, Hazor, the cities of Judah, and Babylon will someday become a den of dragons.
And I will make Jerusalem heaps, and a den of dragons; and I will make the cities of Judah desolate, without an inhabitant. Jeremiah 9:11
And Hazor shall be a dwelling for dragons, and a desolation for ever: there shall no man abide there, nor any son of man dwell in it. Jeremiah 14:33
Behold, the noise of the bruit is come, and a great commotion out of the north country, to make the cities of Judah desolate, and a den of dragons. Jeremiah 10:22
And Babylon shall become heaps, a dwellingplace for dragons, an astonishment, and an hissing, without an inhabitant. Jeremiah 51:37
A dragon lies in Egyptian rivers.
Speak, and say, Thus saith the Lord GOD; Behold, I am against thee, Pharaoh king of Egypt, the great dragon that lieth in the midst of his rivers, which hath said, My river is mine own, and I have made it for myself. Ezekiel 29:3
Micah stripped himself naked while wailing and howling like a dragon.
Therefore I will wail and howl, I will go stripped and naked: I will make a wailing like the dragons. Micah 1:8
God hated Esau, so he made his land a wasteland filled with dragons.
And I [God] hated Esau, and laid his mountains and his heritage waste for the dragons of the wilderness. Malachi 1:3
Someday a big, red, seven-headed dragon with ten horns and seven crowns on its heads will appear in heaven.
And there appeared another wonder in heaven; and behold a great red dragon, having seven heads and ten horns, and seven crowns upon his heads. Revelation 12:3
It will stand in front of a pregnant women, waiting to eat the baby as soon as it's born.
The dragon stood before the woman which was ready to be delivered, for to devour her child as soon as it was born. Revelation 12:4
There was a war in heaven between Michael and his angels and the dragon and his angels.
And there was war in heaven: Michael and his angels fought against the dragon; and the dragon fought and his angels. Revelation 12:7
The great dragon (aka the Devil, Satan) was cast out onto the earth, along with his angels.
And the great dragon was cast out, that old serpent, called the Devil, and Satan, which deceiveth the whole world: he was cast out into the earth, and his angels were cast out with him. Revelation 12:9
When the dragon saw that the woman [Mary?] had a baby boy [Jesus?] he persecuted her.
And when the dragon saw that he was cast unto the earth, he persecuted the woman which brought forth the man child. Revelation 12:13
The earth helped the woman by swallowing the flood that the dragon cast out of its mouth.
And the earth helped the woman, and the earth opened her mouth, and swallowed up the flood which the dragon cast out of his mouth. Revelation 12:16
The dragon was angry with the woman and went to war against her descendants.
And the dragon was wroth with the woman, and went to make war with the remnant of her seed, which keep the commandments of God, and have the testimony of Jesus Christ. Revelation 12:17
The dragon gave the beast a seat and great authority.
And the beast which I saw was like unto a leopard, and his feet were as the feet of a bear, and his mouth as the mouth of a lion: and the dragon gave him his power, and his seat, and great authority. Revelation 13:2
Everyone worshiped the dragon.
And they worshipped the dragon which gave power unto the beast. Revelation 13:4
There was another beast that came out of the earth who spoke like a dragon.
And I beheld another beast coming up out of the earth; and he had two horns like a lamb, and he spake as a dragon. Revelation 13:11
Three unclean frog-like spirits came out of the dragon's mouth.
And I saw three unclean spirits like frogs come out of the mouth of the dragon. Revelation 16:13
The dragon (aka old serpent, the Devil, Satan) was bound for a thousand years.
And he laid hold on the dragon, that old serpent, which is the Devil, and Satan, and bound him a thousand years. Revelation 20:2