Nay. Zodiark from Ivalice differs from FFXIV's Zodiark. In Ivalice, he's always an optional character and summon-related. In the Final Fantasy Tactics, he's a summon with no backstory. On Tactics A2 and Final Fantasy XIV, he's a child Esper with enormous power. Zodiark from Final Fantasy XIV also hails from summoning. Still, he's one of the main antagonists in the bigger picture scenario of the plot that started in A Realm Reborn and ended in Endwalker.