Overlord: Dark Legend
Gnarl is an aged minion who leads the minions between Overlords and acts as the narrator and advisor throughout the conquest. Even though being the frailest minion of the tower, he is the most experienced and knowledgeable, conducting various tasks like restoration of the tower while the Overlord is away and introduces new options and powers to him as they become available. He reflects the multiple paths of corruption the Overlord can take with his tone of voice and speech varying between light and black humour and always reminds the Overlord "There are evil deeds that need doing". Upon arrival of the previous Overlord he is quick to betrayal but also appears less enthusiastic and reassures that if the current Overlord succeeds that he will "happily take him back".
Overlord: Raising Hell
After the Third Overlord is trapped in the Abyss, he states that while many Overlords have come and gone he had a "soft-spot" for him, with the other minions mourning their loss.
Gnarl serves the same role as he once did. It is revealed in the end cutscene that he may be simply pretending to obey the Overlord, and may even be setting him up to fail by his hand as hinted by his sterotypical evil laugh at the end.
Behind the Scenes
He is voiced by Marc Silk.