More than the other (approved) images here, this feels ripe for naming parallels.

WoL ~ Xemnas
Bartz ~ Xigbar
Cloud ~ Lexaeus
Terra ~ Zexion
Squall ~ Saïx
Zidane ~ Axel
Firion ~ Demyx
Tidus ~ Luxord
Cecil ~ Marluxia
Shantotto ~ Larxene
Onion Knight ~ Roxas

Some fit much better than others, and some Dissidiants could fit multiple roles. If it wasn't for OK being a spitting image, I'd've switched Terra in and put him as Vexen.

*waits for status:deleted combers*