“Beings of strange form and appearance made by the gods in ancient times. Favored with great strength and intellect, the Espers knew power far beyond that of men, but their power made them proud, and at length they sought to challenge the gods.
Seeing this, the gods were angered and struck down their blessed children, and binding their souls and flesh with the Glyph of the Beast, they stole their freedom for all eternity. Now they are bound to live only when summoned by their Glyph, to serve whosoever called them forth.”
A list of the Espers that appear in Final Fantasy XII. They are listed in the order that they are typically obtained during a regular playthrough of the game.
The first Esper that you encounter in the game – you must battle and defeat Belias in order to obtain the Dawn Shard.
The second Esper that you automatically encounter while completing the story – you must defeat Mateus at the end of the Stilshrine of Miriam.
The first optional Esper which can be fought in the Zertinan Caverns which can be accessed via the Ozmone Plain.
Another optional Esper that can be defeated after you have reached the Ozmone Plain for the first time.
Returning to the Barheim Passage after you have reached the Ozmone Plain using the Barheim Key and defeating the third optional Esper.
An optional Esper that can be found at the top of the Mosphoran Highwaste which can be challenged after you have reached the Phon Coast.
An optional Esper that can be fought after you have defeated Judge Bergan at the top of Mt Bur-Omisace (but which is an extremely difficult fight that should be completed later on in the game).
A non-optional Esper that is fought in the Ancient City of Giruvegan as you leave the Great Crystal.
Completing the Three Medallions side quest to gain access to the final chamber of the Necrohol of Nabudis to fight Chaos, an optional Esper.
Another non-optional Esper that is fought at the top of the Pharos of Ridorana.
Famfrit is fought during the regular story when you encounter Doctor Cid in the Pharos of Ridorana.
An optional Esper that can be fought after completing the events at the Ancient City of Giruvegan by returning to the Great Crystal, although it should be saved until later as it is a very difficult fight.
The last optional Esper and the most powerful one. The battle to obtain Zodiark in the Henne Mines is extremely difficult.
Achievement/Trophy
The 
High Summoner Achievement/Trophy is obtained by defeating and obtaining all thirteen Espers.
