Warsmith
A Warsmith of the Iron Warriors Traitor Legion is the equivalent of a Chaos Lord in other, lesser, Legions. Each Warsmith commands a Great Company. Pre-Heresy this would consist of around 1,000 Space Marines; but now they vary enormously.
"We fight the long war, not through vain votions of duty and honour, but through a far purer purpose: hatred. At the height of our glory we were betrayed and cast out by our kin. Guilliman, Dorn, Sanguinius-these are names I curse. Horus, Perturabo, Angron-these are names I revere, names I would follow to the very end. It is this hatred that has sustained me throuh the long millenia. I tend it with bitterness. I nurture it with the deaths of my former brothers. For I know that when the end is upon us and Horus is returned, then the false emperor shall be cast down from his sepulchural Golden Throne, and we shall take our rightful place at the side of Horus, the true Emperor of Mankind." Ferrous Ironclaw, Warsmith of the Iron Warriors Second Grand Company