Yuna, Donna, Isaac, Seymour, Braska... that's FFX... They have lots more of course, look in the script or something.
THen you have Garnet and Eiko from FFIX... Only summoners in those games.
And then you have the other games where you can either give players a job that contains Summoner, or equip a summon to your character like in FFVII and FFVIII.
But if you want plain names... Garnet, Eiko, Yuna, Lenne (x-2), Donna, Isaac, Braska, Seymour, plus other FFX summoners I didnt name...