Vorash

The Vorash is a colossal fish-like creature encountered as a major boss battle in Metroid: Other M. It is seen always dwelling in bodies of lava.

History

First spotting the sea beast in a Pyrosphere tunnel, Samus Aran followed a Vorash and battled it in an ocean of lava, littered with obsidian platforms. A long time after the confrontation, the two battle again in the Blast Furnace Observation. Samus comes out victorious yet again, and watches as the lava beast sinks into its natural habitat, never to be seen again.

Boss Battle

During the Vorash's boss battle, Samus has to avoid Vorash's boulders that it throws, in order to attack it, Samus has to shoot it's eyes so that it becomes distracted, then drag it down with her Grappling Beam, and considering it earlier ate a pod that got stuck in it's mouth, Samus is able to damage Vorash's underside after that.

After a while, it swallows the pod that was stuck in it's mouth, which makes it so that Samus has to damage it while the Vorash is leaping or charging for an attack, she may also grapple a grapple point, this makes Vorash jump out of the lava and, if done correctly, makes Vorash eat the grapple point, which defeats Vorash.

Super Smash Bros. Wii U

While not appearing the game as a stage hazard, Vorash does, however, have a trophy in the game, and it's theme can be used on the Pyrosphere stage.

“	A large, fishlike monster that's more at home in an ocean of lava than underwater. Defeating it may seem like an impossible task at first, but Samus Aran knows how to persevere. By firing her Grapple Beam into its mouth, she pulls it out of the lava like a master angler, leaving it writhing helplessly on land.	„
	~ SSBWU

Trivia

The Vorash seems to have a strange obsession with chasing and trying to eat Samus, as it has tried multiple times doing so, and always looks as excited.
It has a very strong resemblances to the extinct species called Mosasaur, as both are carnivorous creatures that swim, have a piranha-crocodile like mouth, and a long tail, and therefore, it is possible that it was based on the Mosasaur.