Ithrawan Plonek was a Scarran from the soldier caste who served as a spy for the Scarran Empire.
In their search for information on Scorpius, the Scarran Empire discovered the planet where a Diagnosan had created the cooling suit used to keep the hybrid alive. Ithrawan Plonek was sent to the planet, where he arranged a deal with the Diagnosan's partner Grunchlk. Plonek was put in stasis in a cryogenic pod, awaiting Scorpius' return to the planet.
When Scorpius did finally return -- responding to a signal from the neural clone in John Crichton's head -- Grunchlk set a timer to release Plonek after three arns. The Diagnosan Tocot discovered this and went to investigate. His timing was poor, and Plonek came to just in time to kill the Diagnosan.
Scorpius took control of Grunchlk, hoping to buy himself time. Under this influence, Grunchlk advised Plonek that Scorpius was not on the planet but that John Crichton might prove to be valuable to him. Plonek was pleased with this information, but trapped Grunchlk in a stasis pod all the same.
Plonek forced his way into the surgery room and confronted Ka D'Argo and Crichton. They managed to escape the planet's frigid surface, where Plonek easily defeated the Luxan until Aeryn Sun arrived with D'Argo's qualta blade. Armed, D'Argo was able to injure the Scarran and Crichton finished him off by driving an icicle into the wound.
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Ithrawan Plonek is derived from Farscape.