Tiamat

Tiamat, also dubbed Titanus Tiamat, is a giant serpentine daikaiju created by Legendary Pictures that appears in Legendary's 2019 film, Godzilla: King of the Monsters, as a name briefly seen on a monitor. She made her first full appearance in Godzilla Dominion.

Personality
Tiamat is very territorial and will fight other Titans for dominance. When beaten by Godzilla after an intense battle, Tiamat was visibly frightened and submitted to the alpha Titan to save herself from being killed.

Ancient Times
Centuries ago, Tiamat fought and killed a Titanus Kong member when she ventured into his lair.

Godzilla: King of the Monsters
Tiamat was found in Stone Mountain, Georgia, USA, by Monarch, who built Outpost 53 around her. When Ghidorah calls all the Titans, Tiamat breaks free and begins to hunt with her new pack. When the ORCA calls all Titans to Boston, Tiamat does not arrive in time for the battle and does not see Godzilla become the new alpha of all Titans (except Kong).

Godzilla Dominion
Battered and exhausted from his battle with Ghidorah as well as several other rebellious Titans, Godzilla returns to one of his old lairs to rest but immediately senses that something is different. The alpha Titan is suddenly ambushed by Tiamat, who sucks him into a whirlpool. Physically outmatched, Tiamat belches toxic vapor into Godzilla's face and disorients him. With Godzilla blinded and stunned, Tiamat drags him deeper underwater, constricting and slicing into him with her scales. Eventually, the two bring the battle into the lair itself, where Godzilla is able to overpower Tiamat and force her to submit. Defeated, Tiamat retreats back into the ocean, forfeiting the lair back into Godzilla's control.

Amphibious nature
Tiamat can survive both on land and in water.

Hydrokinesis
According to Drew Edward Johnson, Tiamat can manipulate water, specifically maelstroms and waterspouts, to allow her to drag foes to her, even airborne ones.

Razor-sharp scales
Tiamat's body is covered in razor-sharp scales that can cut deep gashes into the skin of other Titans, including Godzilla.

Strength and combat
Tiamat can use her jaws and tail as dangerous weapons in combat. She also uses her serpentine body to strangle her opponents like constrictor snakes.

Toxic vapor
Tiamat is able spew a cloud of toxic vapor from her mouth that is capable of blinding Godzilla momentarily.

Dry land
Though able to survive out of water, as an aquatic creature, Tiamat is at a severe disadvantage on land. When yanked out of the water by Godzilla, Tiamat was swiftly overpowered and forced to submit.