Brother-Captain Gabriel Angelos is the commander of the Blood Ravens' 3rd Company. He carries a guilty conscience for destroying his homeworld Cyrene (one of the recruiting worlds of the Blood Ravens) and agonizes over this continuously, though he does not often speak of it. Only his battle-brothers of the Blood Ravens truly understand his feelings on the matter. Gabriel himself, like most Imperial Soldiers, distrusts aliens immensely; it is for this reason he shows incredible disdain for the Eldar in his encounters with their leader, Farseer Macha (though in the novels, his disdain for them gradually lessens). He has also grown up with Librarian Isador Akios, whom he trusts immensely. His trust was shattered when Isador defects to Chaos and steals the key to unlocking the Maledictum.
Captain Angelos makes his return in Dawn of War II. He appears throughout the single-player campaign in briefings, particularly right after the Tyranid invasion on Calderis, aboard the battle barge Litany of Fury (the same one present in Dark Crusade). He only appears as a playable character on the last mission, when the Blood Ravens have successfully injected the poison extracted from the Tyranid Gene Sample, and are clearing the remaining Tyranid forces on Typhon Primaris. In Retribution, if the player completes the Space Marines campaign, Angelos is rebuilt with extensive bionics and is promoted to Chapter Master of the Blood Ravens to replace the late Azariah Kyras.
Captain/Chapter Master Gabriel Angelos is voiced by Paul Dobson (in Dawn of War, Chaos Rising, Retribution), Brian Dobson (in Warhammer 40,000: Dawn of War II).
Source: Wikipedia, "List of Warhammer 40,000: Dawn of War characters," available under the CC-BY-SA License.