Leviathan

Leviathan, also known as Levia, Leviatan and Leviathn, is a summon that appears in the Final Fantasy series.

A giant sea serpent, he first appeared as a monster that swallowed the party in Final Fantasy II, and went on to become one of the most prominent summons in the series alongside Bahamut, being known by titles such as "the Sea King", or "Lord of All Waters". In the later titles of the series, Leviathan's prominence diminished as Bahamut gained more status and popularity. Leviathan's trademark attack is Tidal Wave, also known as Tsunami, which calls on a massive wave of water to damage all enemies.