The T'Syriél were tall, muscular humanoids native to the planet Shiva IV. United into the Twelve Tribes of T'Syriél, the T'Syriél were ancient rivals of the Human Calian Confederacy, with which they warred for generations en route to building a strong and respected warrior tradition. In 2 ABY, those battles were brought to an end with the signing of the Concordat of Peace, although many disaffected T'Syriél were used as troops by Imperial General Bentilais san Sk'ar's attempt to conquer the world.
During the era of the Galactic Civil War, T'Syriél society was organized into the Twelve Tribes of T'Syriél, which were led by a Demarch. However, there was a significant outcast population, consisting of T'Syriél who had largely organized themselves into bandit groups in the planet's wastes. The T'Syriél had a proud warrior tradition forged from generations of bloodshed, although that had started to decline somewhat by 3 ABY.
For generations, the T'Syriél battled for supremacy on Shiva IV with the Human population of the Calian Confederacy, with the constant bloodshed turning the T'Syriél into fearsome warriors. However, that ended in 2 ABY, when Demarch Kéral Longknife signed the Concordat of Peace with Calian Warlord Aron Peacebringer, uniting the two peoples in friendship. That didn't solve all the problems that ailed the T'Syriél, however—in the months to come, many T'Syriél outcasts forgot their proud ways and lost the spirit that made them formidable warriors.
In 3 ABY, a number of T'Syriél outcasts were hired by Imperial General Bentilais san Sk'ar, a Kaleesh who had been assigned to conquer Shiva IV in the Empire's name. In an effort to drive a wedge in between the Twelve Tribes and the Confederacy, Sk'ar enlisted T'Syriél along with Humans in order to give either side the impression the other had betrayed their peace. A number of T'Syriél fought in specially fitted stormtrooper armor when Sk'ar launched his takeover attempt, only for Peacebringer, Longknife and elements of the Rebel Alliance to team up to foil Sk'ar's plan.
The T'Syriél first appeared in Star Wars (1977) 53, written by Chris Claremont and released in 1981. Most of the art from Star Wars 53 and 54 was not originally intended for a Star Wars story—it was originally intended for Marvel Comics' John Carter, Warlord of Mars series, which had been canceled in 1979. Wanting to use 30 pages or so of fully-penciled artwork, Marvel had artist Carmine Infantino adapt the pages for Star Wars, transforming the native Martians into the T'Syriél.
- Aliens in the Empire, Part 2: To a Traitor Go the Spoils on Hyperspace
- The Complete Star Wars Encyclopedia, Vol. II, p. 260
- "Authors of the Expanded Universe: Chris Claremont" — Star Wars Insider 146