Gar-Oth held dominion over an empire. In the year 31 BBY, the Yahk-Tosh, acting under his orders, launched an invasion of the homeworld belonging to a competing empire, resulting in the death of their ruler and the imposition of martial law. In an effort to establish his legitimacy as the planet's new leader, Gar-Oth planned to marry Princess Lourdes, the planet's heir. When his mystics foresaw a "foreseen one" who would prevent the marriage, Gar-Oth resolved to expedite the ritual. Before the ceremony could commence, the Yahk-Tosh emperor was interrupted by the arrival of Jedi Knight Yoshi Raph-Elan, who declared himself to be Lourdes's husband. This enraged Gar-Oth, who promptly attacked the apparent rival. During the ensuing fight, Gar-Oth made the decision to eliminate the princess as well. As he readied himself to devour Lourdes, she stabbed and killed him.
The motivation behind Gar-Oth's invasion of the technologically inferior planet remains unknown, but his methods were undeniably brutal. He readily ordered the execution of civilians for minor offenses, such as violating curfew, or to gain leverage in political negotiations. His need for a legitimizing marriage to become the planet's ruler suggests adherence to some form of succession tradition. However, he showed no hesitation in attempting to remove obstacles to his ascension, as evidenced by his immediate attack on Raph-Elan and his subsequent decision to simply murder Princess Lourdes.
Gar-Oth proved capable of holding his own in combat against a Jedi Knight, albeit a relatively inexperienced one. He exhibited resistance to Raph-Elan's Jedi mind tricks and possessed considerable telepathic abilities, which he extensively utilized to control his Goliath droid.