Trogaar is the Gordanian ruler of the prison ship who captured Starfire in the episode "Go!". He had also captured a Space Monster, a Locrix, and many other creatures. He was the first villain the Titans ever took down as a team.
In the episode "Go!", he and his minions were chasing after their escaped prisoner, Starfire. However, they crash landed on a small piece of land in Jump City. After Starfire's fight with Cyborg, Beast Boy, Robin, and Raven (who ceased the fighting), she kissed Robin, learned English, and flew off. As they were looking for her, Trogaar made a huge hologram of himself, announcing that they were here to capture Starfire, and if they interfered, he would destroy the city. The Titans found Starfire raiding a movie store of food, and the Titans befriended her. Soon after, Trogaar unleashed his minions to search for her. When they found her, the Titans fended them off, destroying Cyborg's hoodie in the process. Trogaar was enraged and started to charge his weapon, a weapon that was powerful enough to demolish Jump City. Robin ensured the other panicked teens that they would get through it together. Raven teleported them inside the ship, and soon they were discovered. When Trogaar was about to fire the weapon, the five burst into the control room and fought off the rest of Trogaar's minions. Trogaar was about to finish Raven and Beast Boy off when Cyborg re-wired his arm into a sonic blaster and shot Trogaar, simply rendering him unconscious. Soon afterwards, Cyborg built Titans Tower out of the damaged ship, and together they formed the Teen Titans. What becomes of Trogaar and his army remains unknown, but it's possible that they left Earth and went back home.