Leviathans are utterly enormous puppets designed for ferrying smaller puppets through the depths of space. Their colossal wings act as both anchors and extraction sails, harvesting energy from the cosmic microwave background and allowing them to propel themselves to even superluminal speed with some buildup. They are seldom found in groups, but when they are, a group of Leviathans is called an eclipse.

Blending the line between kilostructure and organism, the Leviathan is an enormous puppet, standing at an enormous 520' (15850cm). Their colossal bodies are highly adapted for a vacuum environment, with thick shelled plates running the length of their back to aid in pressure mediation. They also have a crest of these plates around their necks, as well as a distinct set of plates that protect their underbellies. They also have three large pairs of wings for traversing both in and out of atmosphere, and sport six legs to ease the pressures of landing on planets. They also sport three extra pairs of eyes, widening their field of view and allowing them to accurately determine depth out to substantial distances.

Internally, Leviathans sport a very strange and robust body structure: Their interiors are trifurcated vertically, with the lowermost "deck" being reserved for their internal organs and other life-preserving equipment. The middle deck, running the length of their barrel, is one of two habitation decks for passengers and supplies. Lastly, the upper deck is the largest occupiable space, running from behind the eyes to the tip of the tail (additionally giving access to the narrower spaces inside their hollow mane spines). The Leviathan regulates its internal gravity such that they host localized biospheres, which many Leviathans take great pride in.

Providing access to the habitation decks are four large natural openings. All of the openings always share a side, allowing the Leviathan's other side to be completely reserved for structural support. Each port has a pair of large, keratinized blast doors that can be closed at the Leviathan's will, usually during take off or landing. Otherwise, the doors can be sealed by a psionic membrane similar to a Delta's shields, keeping air in and hazards out while in a vacuum.

Leviathans are purpose-built for interplanetary transport. Their size, in particular, is a key part of their operational strategy: A Leviathan must be large enough to not only house, but also feed and care for vast numbers of puppets, including Titans. The biospheres they maintain are receptive to puppet magic, allowing smaller puppets to work fields even while in flight, providing a consistent source of nourishment even if a flight would take months or years.

A Leviathan's wings are key to its survival and function. While not particularly physically impressive, they serve a crucial role as regulatory nodes for colossal psionic fields that the Leviathan uses to interact with the cosmic microwave background. While this is primarily for propulsion purposes, allowing the Leviathan to push off of what would otherwise be innavigable vacuum to maneuver as needed. They also, however, harvest the microwave background for energy, allowing them to sustain themselves without the light of a star. If a Leviathan needs to accelerate beyond its normal cruising speed, it can also use its fields to unleash a substantial amount of energy, accelerating or decelerating up to 90% the speed of light with enough wind-up.

Despite these incredible feats of survival and navigational strength, Leviathans are unarmed aside from their size. This is typically compensated for by having their doors open, allowing smaller puppets like Perditioners or Auroras to fire out at would-be targets.

Leviathans, being so purpose-built for travelling, display a strange mix of grogginess and wanderlust. They often appear to sleepwalk while on planets, allowing the needs of the gestalt to guide them. They are also capable of entering a full hibernation state, during which the Leviathan rests and allows its body to function according to the clan's needs (usually acting as the start of a puppet colony on a new world).

While Leviathans appear very different to most puppets, they can trace some of their epigenetic lineage back to Deltas, and their hard scaly plates are partially alloyed with a material similar in chemical structure to Haetanium. How these alloyed cells are created by Archmothers or non-Mechanized Archons is unknown, but most schools of thought consider it a form of convergent evolution.

I... Distinctly remember when it finally occurred to me that, one day, our home would not be big enough for all of us. We take good care of it, and we love it very much, but the fact of the matter is that we would eventually run out of space. I'm not proud to admit that sent me into a panic, though like all of my sudden stresses, it usually serves a purpose. I started spawning, well... Something enormous, frankly. A heart alone took dozens of spawns. A leg took nearly a hundred. Piece by piece, the solution became clearer, and we prepared a space for it. The beast that came to us in our time of need was nothing short of incredible. One so great that only its size could define it: A Leviathan.

Despite their size, the Leviathans are about as harmless as a titan can come. They only wish to help us navigate the stars, protecting us from frontiers that would seek to claim us. Their temperament is so gentle, you might see one nuzzle a single Agent with little issue. It makes me happy to know that even at such scales, my children are still able to get along with one another.

I didn't really ever intend to make a puppet larger than a Cambrian, but the idea of a puppet that acted as a worldship is something that's been stalking me for a long time. Combine that with some inspiration from the Behemoths from Stellaris and you get a giant colony ship space dragon horse.