Zai Vessalius

Oz and Ada's father. Appeared only in a flashback until chapter 39. He is depicted with a cold attitude toward his son and explicitly rejected him.

In chapter 40

[Spoiler] it is shown he has a large scar across his face and is responsible for sending his son to the Abyss. He controls the Griffin chain. Although the Duke Nightray tells Elliot to hate the Vessalius, he and Zai seem to be friends. [/Spoiler]

(Source: Wikipedia)