Leviathan

Leviathan, also dubbed Titanus Leviathan, is a prehistoric giant aquatic created by Legendary Pictures to appear in the MonsterVerse. It is currently unknown if Leviathan is seen in Legendary's 2019 film, Godzilla: King of the Monsters, besides its name appearing on a monitor, but it is briefly mentioned in Godzilla: King of the Monsters - The Official Movie Novelization.

Name
The "Leviathan" likely refers to the Biblical use, in which the Leviathan is a giant sea creature created by God, usually described as a serpentine crocodile or a whale. This creature is the counterpart to the Behemoth. Leviathan's name may also refer to the definitions of "leviathan", either a large aquatic creature or a thing that is very large or powerful.

Godzilla: King of the Monsters
Leviathan was found in Loch Ness by Monarch, and an outpost was built around it. When Ghidorah calls, Leviathan breaks free of its outpost and begins to hunt with the other Titans. When the ORCA calls all Titans to Boston, Leviathan does not arrive in time for the battle and does not see Godzilla become the new alpha of all Titans but Kong.

Trivia

 * It is unknown how Leviathan broke free of the Monarch Outpost and destroyed human settlements, as it is trapped in a lake and is not mentioned to be amphibious like Godzilla or Scylla.

Films

 * Godzilla: King of the Monsters

Novels

 * Godzilla: King of the Monsters - The Official Movie Novelization