Summoners, also localized as Caller, use Summoning Magic.
Summoner from Final Fantasy Tactics
Summoning Magic calls on powerful entities known as "Call Beasts" (Final Fantasy IV), "Espers" (Final Fantasy VI and Final Fantasy XII), "Guardian Force" (Final Fantasy VIII), "Eidolons" (Final Fantasy IX, Final Fantasy XIII, and the DS version of Final Fantasy IV), "Aeons" (Final Fantasy X), "Avatars" (Final Fantasy XI), "Primals" ("Final Fantasy XIV"), or simply "Summon Monsters" (most other games in the series).
These entities attack enemies, protect the party, or render other forms of aid. Summoners often use commands such as "Summon," but in the original translation of Final Fantasy IV, the command was instead known as "Call". As a magic-using class, summoners are typically shown to be physically frail as a trade-off for high magical potency, and can traditionally equip only light armaments such as clothing and robes.