Divine Divinity Edit
Most of Divine Divinity takes place in the duchy of Ferol and its Duke, Janus Ferol, is a major character in the game. It's unclear how far its borders extend; parts of the Dark Forest don't seem to be entirely part of Ferol, and it's unclear whether or not Aleroth is within the duchy. The Farmlands seem to be within its borders, however, and Verdistis is either within Ferol or directly bordering it.
Divinity II: Ego Draconis Edit
The duchy is referenced by some of the literature in Ego Draconis, and was the Dragon Knight's homeland according to flavor text. While the Dragon Knight can't enter Ferol proper (unless Aleroth is a part of the duchy) they can visit the path to it, but will be blocked by Kali's Flying Fortress.
Divinity: Original Sin Edit
Although Ferol itself isn't featured in the game, the current Duke of Ferol makes an appearance in Cyseal and, according to legend, Cyseal itself was founded by two former citizens of Ferol.
The Adventures of Fabian of Ferol - A quest item in possession of the Slayer at the start of the game.