Leviathan

Leviathans are giant sea creatures.

Skyward Sword
In Skyward Sword is the giant squid Tentalus which has the title "Abyssal Leviathan" found in the Lanayru Sand Sea the site of an Ancient Sea.

Breath of the Wild
Leviathans are ancient whales thought to have gone extinct many thousands of years before. There are bones located high up in the Hebra Mountains, Eldin Mountains, and the Gerudo Desert. There are researchers that each have a theory as to why they died out. One believes they died out during a great ice age.