An alien species first encountered around 2040 by the 117th Large-Scale Research Fleet. Initially, they were non-hostile toward humanity, but this seems to have changed in more recent years, as they begin mounting attacks on the Frontier Fleet. They serve as the primary antagonists for the series.
- Adaptive Ability: Initially, their outer skin was tough enough to stand up to shells and missiles pretty easily. This makes the humans break out the Reaction weapons against them, and then they start encasing themselves in a reactive exoskeleton that can weather such assaults. This forces the humans to start using DME weaponry...
- Bizarre Alien Biology: Their physiology completely baffles the human scientists who study them. They have a decentralized nervous system (ie, "no brains") which doesn't seem to have nearly enough neural pathways to support the intelligence the Vajra clearly possess, they have what amounts to a natural FTL Drive in their body (technically, Protoculture Fold technology was reverse-engineered from Vajra organs in the distant past: the Vajra came first), and they communicate by means of psychic bacteria in their guts, which maintains their Hive Mind.
- Hive Mind: A true hive mind at that: there is no central controller, no individuality. The entire species is one mind and one will.
- They can seem capable of a level of inividuality, as shown by Ai-Kun, but they had to learn the concept from contact with Humanity first.
- Hive Queen: Subverted. Vajra Queens act as communication nodes and have a greater amount of brain matter in them than other Vajra, but they are not individuals nor do they control the others. Grace uses the primary Queen at their homeworld as an entry point to their Fold Network, making herself a de facto Hive Queen.
- Kaiju: Even the smallest adult Vajra are about the size of a bus, while the larger ones, such as in the picture, can stand nearly twice as tall as a macronized Zentraedi. The Queens are the outliers even among their race: a minor Queen encountered partway through stands a fair bit larger than the largest drones, while the primary Queen at their homeworld stands several kilometers tall. Surprisingly, larval Vajra start out about the size of a large squirrel as demonstrated by Ai-kun.
- Organic Technology: All of their ships appear to be organic in nature, though it isn't clear whether the ships themselves are another form of Vajra or just constructs grown by them. They also integrate some organic technology into their own bodies, including Fold Engines, explosive growths that function like missiles, and what appears to be a back-mounted railgun on larger Vajra.
- Poor Communication Kills: The entire reason there's a conflict with them at all. They attempted to implant their communication bacteria into humans to talk to them, but said bacteria caused the lethal V-Type Infection. When a human was successfully linked with their network (Ranka), they mistook her for one of their own being held captive by humans and launched attacks to "rescue" her. Once they realized their mistake, they had no way of apologizing to the humans for the misunderstanding.
- Precursors: They are old enough to remember the Protoculture, who had some limited contact with them way back when. Some of the Protoculture's most advanced technology is believed to have been copied from the Vajra's own natural systems.
- Reactionless Drive: it isn't entirely clear how they propel themselves through vacuum. They make movements as though "swimming", and their tails glow brightly when they do, but the actual method isn't gone into. It also works in atmosphere, coupled with using insect-like wings on their backs for maneuvers.
- Starfish Aliens: The closest analogue would probably be eusocial insects, but the Vajra have several major differences even from them.
- Subspace Ansible: How they maintain their Hive Mind. It's a naturally-occurring one made up of the bacteria in their digestive tract.