Dragons show up thematically in many mythologies:
Norse: Jörmungandr is the "world serpent"
According to the Prose Edda, Odin took Loki's three children by Angrboða — the wolf Fenrir, Hel, and Jörmungandr — and tossed Jörmungandr into the great ocean that encircles Midgard. The serpent grew so large that it was able to surround the earth and grasp its own tail. As a result, it received the name of the Midgard Serpent or World Serpent. When it releases its tail, Ragnarök will begin.
Christianity: Satan is depicted as the serpent
Genesis 3:1 NIV
Now the serpent was more crafty than any of the wild animals the Lord God had made.
And again in Revelation
Then another sign appeared in heaven: an enormous red dragon with seven heads and ten horns and seven crowns on its heads. 4 Its tail swept a third of the stars out of the sky and flung them to the earth. The dragon stood in front of the woman who was about to give birth, so that it might devour her child the moment he was born. 5 She gave birth to a son, a male child, who “will rule all the nations with an iron scepter.”[a] And her child was snatched up to God and to his throne. 6 The woman fled into the wilderness to a place prepared for her by God, where she might be taken care of for 1,260 days.
7 Then war broke out in heaven. Michael and his angels fought against the dragon, and the dragon and his angels fought back. 8 But he was not strong enough, and they lost their place in heaven. 9 The great dragon was hurled down—that ancient serpent called the devil, or Satan, who leads the whole world astray. He was hurled to the earth, and his angels with him.
Chinese: Dragons are quite prevalent in Chinese mythology:
Chinese dragons or East Asian dragons are legendary creatures in Chinese mythology, Chinese folklore, and East Asian culture at large. East Asian dragons have many animal-like forms such as turtles and fish, but are most commonly depicted as snake-like with four legs. They traditionally symbolize potent and auspicious powers, particularly control over water, rainfall, typhoons, and floods.
There are many additional listings found on the Wikipedia page below including the Hydra (Greek), Tiamat (Babylonian), and the Tarasque (French):