Kirishiac are a species of First Ones that briefly allied with the Army of Light to end the Shadow War.
The Kirishiac evolved on the planet Kirish, which has such pressure extremes that the atmosphere is almost liquid. The gravity on the planet is almost hellish. Kirishiac are bipedal, and are uniquely adapted to survive the extreme air pressure. Their cells are arranged in complex, lattice-like structures, yet they are almost translucent. Due to the high gravity, Kirishiac have eight hearts to pump blood against the gravity. Typically they can be up to seven meters (23 feet) tall.
For a while, they began to wander into nearby space, conquering/enslaving/sometimes killing younger races. For a while, they continued expanding their empire, until they discovered Hyperspace. Then they began to wander into the territories of older first ones, and a short war ensued. After the futile conflict, the Kirishiacs were sent packing back to Kirish.
The Kirishiac "Lords" (when talking to other, Younger Races, they prefer to be called this. Obviously, they are still very arrogant) are resistant to most kinetic weapons, so they soon developed chemical and energy weapons due to their aggressive nature. These large beings travel in impressive ships that share some traits with the much older Avatar 3-class Capital Ship. However, Lordships use different weapons and developed their shared armor and propulsion with the Avatar 3 independently.