The Grand Ruler/Emperor or Empress of Tamaran is a monarch who is the leader of the planet Tamaran.
The current Grand Ruler is Galfore. One of Starfire and Blackfire's parents was the Grand Ruler at one point, with a consort sharing the throne. Blackfire was also Grand Ruler of Tamaran for a short while, but only for selfish and power-hungry purposes. Starfire defeated her and was crowned Grand Ruler herself, but gave the crown to Galfore, saying that she wasn't best for Tamaran. The identity of the Grand Ruler before Blackfire is unknown, as both of her parents were already dead and Wildfire was still missing at this point in the timeline. The Grand Ruler can be challenged to a fight for the crown, which must be a one-on-one fight.