Syn Shenron (一星龍, Yī Xīng Lóng; literally One-Star Dragon; Blue Waters dub Ii Shenron, in Spain: Ih Shinron/Super Ih Shinron) is the seventh and last of the Evil Shadow Dragons to appear, and the last villain to appear in Dragon Ball GT. He later transforms into Omega Shenron after absorbing all seven of the Dragon Balls into his being (this is his special power, rather than having power over elements). As Omega Shenron, he is the strongest and final villain in the series and the second strongest character overall, only eclipsed by Gogeta in his Super Saiyan 4 form.
As revealed in Dragon Ball GT Perfect Files he was born from the wish made by Mr. Popo to revive everyone on Namek that was killed at the hands of Frieza and his soldiers. The sheer scale of this wish (in fact, it was the only one that made Shenron wonder if he had the power to grant it) produced a tremendous amount of negative energy, accounting for Syn Shenron's overwhelming power, while the selflessness of the wish (made to restore Namek's dragon in order to wish the population away from the dying planet) accounts for his purely evil nature.