Octavius Rabelaq was a Colonel of the Imperial Guard. Commanding the 10th Logres Regiment, Rabelaq displayed great heroism during the Battle of Tarsis Ultra. During the battle, he led the defense of Tarsis Ultra's capital of Erebus from his Capitol Imperialis. When the defensive positions around Erebus were being overrun by the Tyranids, Rabelaq charged his vehicle into the enemy ranks. While this bought time for his Regiment to withdraw, it doomed Rabelaq and his crew to a grisly death at the hands of a Bio-Titan.