Brother Dusk is a key character in the Apple TV+ series Foundation, representing the eldest of the ruling Genetic Dynasty of clones, serving as a retired emperor in an advisory role to the current emperor, Brother Day, and the successor-in-training, Brother Dawn. Portrayed by actor Terrence Mann, he is a powerful, opinionated, and often ruthless figure who has lived through many cycles of the dynasty, making him a repository of history and a formidable player in the empire's politics.