You can’t really have a collection of monsters and not mention the Kraken! And one of the best places to see this nasty monster in action is Disney’s 20,000 Leagues Under the Sea!
In the meantime, start your popcorn poppin’ and read this:

The kraken (/ˈkrɑːkən/) is a legendary sea monster of gigantic size and cephalopod-like appearance in Scandinavian folklore. According to the Norse sagas, the kraken dwells off the coasts of Norway and Greenland and terrorizes nearby sailors. Authors over the years have postulated that the legend may have originated from sightings of giant squids that may grow to 13–15 meters (40–50 feet) in length. The sheer size and fearsome appearance attributed to the kraken have made it a common ocean-dwelling monster in various fictional works. The kraken has been the focus of many sailors passing the North Atlantic and especially sailors from the Nordic countries. Throughout the centuries, the kraken has been a staple of sailors’ superstitions and mythos.

Etymology
The English word kraken is taken from the modern Scandinavian languages, originating from the Old Norse word kraki. In both Norwegian and Swedish Kraken is the definite form of krake, a word designating an unhealthy animal or something twisted (cognate with the English crook and crank). In modern German, Krake (plural and oblique cases of the singular: Kraken) means octopus, but can also refer to the legendary kraken. Kraken is also an old Norwegian word for octopus and an old euphemism in Swedish for whales, used when the original word became taboo as it was believed it could summon the creatures.

Read more about this here at Wikipedia!