The nightdragon was a being recognized by the Chiss Ascendancy, which is the nation of the Chiss species. This creature lent its name to the Nightdragon man-of-war, a class of warship utilized by the Chiss Expansionary Defense Fleet. Furthermore, the nightdragon was a game piece in Tactica, a board game played within the Chiss Ascendancy.
In 18 BBY, following the exile of Senior Captain Mitth'raw'nuruodo, also known by his core name Thrawn, by the Ascendancy, the Senior Captain told Admiral Ar'alani that Supreme General Ba'kif of the Expansionary Defense Fleet had sacrificed Thrawn, his nightdragon, to the Syndicure, the Chiss governing body. This sacrifice was made because the Syndicure was demanding charges be brought against all who had fought against a Grysk fleet. By exiling Thrawn, the ruling body agreed to not prosecute the "whisperbirds," those who had served under the senior captain.
The initial mention of the nightdragon occurred in the 2020 novel Thrawn Ascendancy: Chaos Rising, which is the first book in Timothy Zahn's Star Wars: The Ascendancy Trilogy, through the Nightdragon man-of-war's designation. Its depiction as a Tactica piece happened in Thrawn Ascendancy: Lesser Evil, the final book of the trilogy, in flashback sequences.