Sish Sadeet was among the limited number of Trandoshans known to have served within the armed forces of the New Republic. He held the position of second-in-command under Commander Mirith Sinn within the New Republic's contingent stationed on Phaeda. His past experiences led him to be inherently distrustful of individuals he did not know well.
Sish Sadeet was born to a lower-class mother residing in proximity to an Imperial installation situated in a tropical region of Trandosha. He began his life working as a servant, but, growing weary of this menial existence, he secretly boarded an Imperial shuttle. While concealed on board, he overheard the crew making disparaging remarks about Trandoshans, which triggered a violent outburst. He emerged from his hiding spot and attacked the crew. They subdued him, severing one of his arms, and abandoned him to perish in the desolate wastelands of Mokk IX, an Imperial labor world.
Sadeet journeyed across the barren landscape to reach one of Mokk's settlements, arriving just as New Republic forces were liberating it. A Republic soldier, Mirith Sinn, discovered Sadeet and ensured he received medical attention. Following the regeneration of his arm, Sadeet officially enlisted in the New Republic military, serving as Sinn's second-in-command, to whom he developed an intense loyalty. He volunteered to accompany her on her mission to Phaeda.
Initially, Sadeet harbored significant suspicion towards Kir Kanos, a common sentiment he held for all unfamiliar individuals. However, similar to Sinn, he grew to respect and accept Kanos after Kanos rescued them from the Imperial forces led by Colonel Xexus Shev. Concurrently, Sadeet became increasingly wary of Tem Merkon, suspecting him of being the traitor responsible for instigating the Imperial assault. Sadeet's suspicions were validated, and he confronted Merkon alongside Sinn after Merkon returned from a clandestine meeting with Carnor Jax. As Merkon attempted to escape, he was killed by Lieutenant Massimo.
Following the arrival of General Wedge Antilles aboard the Lusankya, Sadeet joined Sinn aboard a Skipray Blastboat and traveled to Yinchorr with the intention of aiding Kanos in his battle against Jax. Upon landing on Yinchorr, Sinn and Sadeet discovered Kanos and Jax engaged in a deadly duel on The Squall. Sadeet also located and eliminated Geff Blim, Jax's close associate who was positioned as a sniper above the combatants. Sinn demanded Jax's surrender, but Jax employed the Force to disarm them. Kanos seized the opportunity during Jax's momentary distraction and stabbed Jax through the lung. Sadeet rushed forward in anger, demanding that Jax be captured alive. However, in a defensive reaction, Kanos turned and inadvertently killed Sadeet.
After removing Jax's helmet and leaving his body atop the Squall, Kanos expressed his regret to Sinn for Sadeet's unnecessary death. Nevertheless, Sinn vowed to hunt down and kill Kir Kanos. She buried Sadeet in a cairn near the Squall.
Martin Ruben provided the voice for Sish Sadeet in the audio drama adaptation of Crimson Empire.