- "Whatever the original Thrawn might have done, this particular being hasn't done anything wrong. Certainly nothing that deserves a summary execution."
- ―Luke Skywalker
During his campaign against the New Republic, the Chiss Grand Admiral Mitth'raw'nuruodo sent a single Spaarti cloning cylinder to his facility on Nirauan to create a clone of himself. Intended as a fail-safe in the case of Thrawn's death, the clone remained in his cylinder beneath the facility for almost ten years. But in 19 ABY, the clone was discovered by Jedi Master Luke Skywalker and the former Emperor's Hand Mara Jade, and the clone was destroyed when the cylinder's generator was overloaded in a fight with the facility's defenders.
Luke Skywalker, Mara Jade, and R2-D2 discovered Thrawn's clone during a mission to Nirauan in 19 ABY. He was still growing inside his Spaarti cloning cylinder, but was nearly mature. Luke and Mara believed him to be the intended fulfillment of Thrawn's claim that he would return ten years after his death. 
An elaborate system of defenses was in place around the developing clone. These included a distracting audio-visual recording, loops of cord that sprouted from the floor to trip attackers, and two sentinel droids equipped with blasters and cortosis armor. A pair of ysalamiri were also present near the cloning cylinder.
Upon finding the clone, Luke and Mara debated the ethics of killing him and decided against it. A short time later, however, they were attacked by the sentinel droids. During the battle, the chamber began to flood with water from the Lake of Small Fish outside the fortress.
Trapped by the rising water and facing imminent death, Luke and Mara devised a plan to escape by making the Spaarti cylinder's power generator explode. This enabled them and R2-D2 to survive, but killed Thrawn's clone in the process.
- The Essential Chronology
- The Official Star Wars Fact File 102 (CAA2, Caamas Document)
- The New Essential Chronology
- The Complete Star Wars Encyclopedia, Vol. II, III ("Hand of Thrawn," "Thrawn, Grand Admiral")
- The Essential Guide to Warfare
- The Essential Reader's Companion