Diethard Ried is a 32 year old member of the Black Knights initiially as the Head of Information, Espionage and Public Relations. But following the restructure he became the Secretary of Media and Intelligence before finally siding with Prince Schneizel el Britannia.
Diethard was a Britannian who worked as the producer of Hi-TV, and was obssessed over Zero after he saw him when he took control over Jeremiah Gottwald and saved Private Suzaku Kururugi from being executed by Britannia. Reid soon joined the Black Knights and gained the positions which made him in charge of intelligence and media. Diethard soon sided with Second Prince Schneizel el Britannia as he thought his plans were more interesting, although he admitted he would prefer it if Zero toppled over Britannia instead. When the geassed Democles guard restrained both Earl Kanon Maldini and Diethard, then Zero took control over Schneizel with his Geass, Diethard enraged of Zero being still alive. The furious Diethard shot one of the guards dead and got Lelouch at gun point but the controlled Schneizel shot him. Diethard, in his dying words, requested for Zero to finish him off with his Geass but Lelouch claimed Diethard isn't worthy and so he died.