I got a lot to think of when it comes to Final Fantasy characters. So here's who's who in my mind:
Warrior of Light
Firion
Luneth
Cecil Harvey
Bartz Kleuser
Terra Branford
Cloud Strife
Squall Leonhart
Zidane Tribal
Tidus
Shantotto
Vaan
Claire "Lightning" Farron
Serah Farron
Noel Kreiss
Noctis Lucis Caelum
Machina Kunagiri
Rem Tokimiya
Princess Sarah
Maria
Refia
Rosa Johanna Farrell
Kain Highwind
Rydia of the Mist
Edge
Lenna Charlotte Tycoon
Faris Scherwiz/Sarisa Scherwil Tycoon
Celes Chere
Locke Cole
Tifa Lockhart
Aerith Gainsborough
Vincent Valentine
Yuffie Kisaragi
Rinoa Heartilly
Selphie Tilmitt
Irvine Kinneas
Zell Dinche
Quistis Trepe
Garnet Til Alexandros XIV
Adelbert Steiner
Beatrix
Freya
Yuna
Auron
Wakka
Lulu
Rikku
Paine
Prishe
Penelo
Ashelia B'nagrin Dalamasca
Snow Villiers
Sazh Katzroy
Hope Estheim
Oerba Dia Vanille
Oerba Yun Fang
Paddra Nsu-Yeul
Ignis
Gladiolus
Prompto
Stella Nox Fleuret
Ace
Sice
Seven
Nine
Queen
King
Lumina
Garland
Emperor Mateus
Golbez
Exdeath
Kefka Palazzo
Sephiroth
Ultimecia
Kuja
Jecht
Vayne
Galenth Dysley
Caius Ballad
And this long list may update because there are a lot of FF characters I have in mind... X3