Reaper Leviathan

The Reaper Leviathan is currently the largest aggressive life form in Subnautica, belonging to the fauna category.

Currently the Reaper cannot harm the Cyclops, though it has enough strength to push it.

If fins and head protrusions are included, the Reaper Leviathan  currently is about 2.5 times higher and about 10 times longer than the Seamoth.

Several Reaper Leviathans reside near the Aurora, guarding the area. However, it mainly dwells vast, open biomes like the Dunes and the Mountains.

Appearance
The Reaper Leviathan is a colossal creature. It has a long, slim, muscularly built body with four caudal fins and two pectoral fins, with all of the latter brown tipped. It also has two dorsal fins running along the length of its entire body, and two ventral fins taking a small portion of its belly. Most of its fins, along with its back, are red in color.

On its head features a large mouth, as well as two pairs of green eyes along with large red, brown tipped mandibles on each side, resembling a large ram. Most of the body is blue-shaded white in color, having a seemingly smooth skin.

Behavior
The Reaper Leviathan usually emits loud, echoing roars which can be heard from very far away.

It also seems to circle its prey (or more commonly the player) for a few moments before attacking, and often strikes from behind by surprise.

Abilities
The Reaper Leviathan is able to instantly kill any players it attacks outside of their submarine. It is also capable of grabbing the Seamoth and shake it around, doing so would deal about 40 - 45% damage to the vehicle before letting go.

The Reaper Leviathan has been observed to grab a Seamoth and smash it down to the seabed, destroying it completely afterwards.

Trivia
There is a small possibility that the Reaper Leviathan actually Defensive because in the gif below and the test I did, if you look closely at the person had drives the Seamoth into the Reaper Also if it was meant to be aggressive it would most likely attempt to destroy a Cyclops by attack with its head, teeth, and the claws. P.S. If I am wrong feel free to remove this Trivia.

Gallery
For a more complete gallery, visit Reaper Leviathan/Gallery.