Kraken

Every sailor must beware of these huge beasts at sea. The Kraken attacks ships which it feels are disturbing it, but people near the shore also aren't safe from it's tentacles, which lash out at everything moving. To fight against these things is hard and only the most powerful warriors can win in such a duel.

Kraken roam the open sea and many smaller waters.

In Ultima I, it is called a Giant Squid, in Ultima III a Man-o-War, in Ultima IV and V Squid, in Ultima VI Giant Squid, But they act all the same. In Ultima VII and VII/2, this changes, and only one tentacle of the Kraken is seen, which also can be fought from land (It can't attack ships any more).

Lore
''When tentacles of the Giant Squid close around a man or a ship, the very power of lightning is released upon the prey. 'Tis best to try to destroy the evil Squid with cannon fire before it can engage thee at close quarters."

- from "The History of Britannia", Ultima IV