Soldiers of the Empire! We stand at the dawn of a new age! The lost power of magic has returned to us! We are the chosen ones! The time has come for us to claim our rightful dominion over the world! Nothing shall stand in our way!
Gestahl has long white hair, a white beard and mustache. Being an emperor, Gestahl dresses in ornate robes and golden plates over red clothes lined with gold. He wears a black gold-lined head ornament that sustains a ruby.
There is some confusion on Gestahl's age from the source materials. The Final Fantasy VI The Complete guide and 20th Anniversary Ultimania give his age as 50 yet in the timelines given in the Final Fantasy VI Settei Shiryō-hen he was born 72 years before the events of the game, and became Emperor around the age of 50.
Gestahl's ambition is to project power over the world and use technology to make his Empire grow unparalleled in its military branch. Gestahl is ruthless in attaining his goals, shown in his forceful taking of espers and paying no mind to the experiments done to them. Not once did he show remorse regarding the ethical ambiguity of infusing children with magic or using a mind-controlling device.
Gestahl holds little regard for human and intelligent life, having his eyes set only on his dream Magic Empire. Even after Kefka's atrocities the Emperor does not punish him outside of throwing him into a prison cell. Gestahl's fake affability and attempt to trick and use the party to his own ends, after lying to them, shows his political knowledge. Gestahl attempts to stop Kefka's disturbance of the Warring Triad as his goal is to lead an Empire, and not to destroy the world, although in the SNES version he laments that no one will worship him.
Gestahl wields the power of magic, and can cast powerful high level spells during his battle against Kefka. Gestahl has likely been using magicite to learn magic. The spells used against Kefka are in order of appearance: Firaga, Flare, and Meltdown.
Born to a military family in the southern state of what would become Vector in the Gestahlian Empire several decades ago, Gestahl's father was involved in a military coup while he was 13 years old, and Gestahl crowned Emperor some time later. During his time as Emperor, Gestahl researched ancient tales of magic and sorcery, looking for truth behind the tales.
The exact details of Gestahl's rise to power (outside of his father being involved in a coup) are unknown, but he came to lead Vector some time before his scholars located the portal to the Esper World beyond the Cave to the Sealed Gate. Gestahl led a raid to capture espers, but he and his troops were ejected when the esper elder cast a spell to seal the gate. In the chaos, the esper Maduin and a human woman Madeline were swept out and, outside the gate, Gestahl found Madeline's daughter, Terra and took her, Maduin and the other captured espers back to Vector.
The next several years would see the rise of Magitek making the Empire the most powerful force on the planet as they rediscovered the secrets of magic. Owing to this, Gestahl made a manifesto declaring their intent to conquer the planet. At some point during one of their attempted conquests, the Siege of Doma, Gestahl had summoned General Leo back to Vector for an unspecified duty. This made him indirectly responsible for the poisoning of Doma shortly thereafter, as Kefka, who had been assigned command of the operation, proceeded to dump poison into the river to ensure a victory for the Empire. When the Returners open the Sealed Gate more espers emerge and destroy Vector and the Returners that come to the Imperial Palace in the aftermath are treated to dinner with Gestahl, who claims he has lost his will to fight at the sight of how powerful and angry the espers were, and the losses his Empire has sustained. Gestahl asks the Returners to accompany a force of Imperial soldiers lead by General Leo to Thamasa to locate the espers and negotiate peace. This is a ruse, however, as Gestahl dispatches Kefka to the village to turn the espers into magicite. Kefka kills Leo and burns the village, reportedly telling Gestahl Leo was a traitor.
With the power gained from the espers in Thamasa, Gestahl and Kefka cross into the esper realm and raise the Floating Continent with the power of the Warring Triad. The Returners land on the continent and confront Gestahl who uses the power of the Triad to paralyze them, leaving only the former Imperial general, Celes. Gestahl and Kefka hand Celes a sword and offer her the chance to rule the world with them if she proves her loyalty and dispatches her friends, as well as hinting that Gestahl desires Celes and Kefka produce Magitek progeny. Celes refuses and stabs Kefka who flies into a rage and demands the Warring Triad to reveal their true power.
Gestahl, knowing that the Triad's true power could destroy the world, tries to stop Kefka but Gestahl's spells are ineffective against him as Kefka is protected by the statues' forcefield. Gestahl is struck down by a bolt of lightning from the Triad and Kefka kicks him off the side of the Floating Continent to his death, marking the end of the Gestahlian Empire, although not before Gestahl laments that Kefka's actions will result in the world knowing true fear.
The theme song for Gestahl and his army is called "Troops March On" or "Empire Gestahl." This plays in scenes involving him or his army. It is similar to the famous song "Bolero".
Gestahl appears as a dog minion. This is likely a reference to the fact Gestahl's original SNES sprite resembled a dog.
Emperor Gestahl appears with one Fire- and one Dark-elemental card.
The name Gestahl may derive from Gestalt psychology. Gestalt psychology or gestaltism (German: Gestalt "shape, form") is a theory of mind whose central principle is that the mind forms a global whole with self-organizing tendencies. This principle maintains that the human mind considers objects in their entirety before, or in parallel with, perception of their individual parts; suggesting the whole is other than the sum of its parts. Gestalt psychology tries to understand the laws of our ability to acquire and maintain meaningful perceptions in an apparently chaotic world. In psychology, gestaltism is often opposed to structuralism.
- After the banquet with Gestahl and before leaving for Thamasa, it is possible to talk to the Emperor. In the North American Super Nintendo Entertainment System release, the name shown in his textbox is "Majesty", while he is known as "Gestahl" in the Finest Fantasy for Advance release. Kefka does refer to Gestahl by his real name shortly before Leo ended up killed in both versions.
- There is a portrait of Emperor Gestahl in Owzer's Mansion.