Simion Pentasian was the Master of the Administratum during the Horus Heresy. A dour and humorless man, Pentasian was nonetheless a faithful servant of the Imperium who managed to hold together the vast Administratum.

西蒙·彭塔西安是荷鲁斯叛乱时期的内务部长。彭塔西安是一个沉默寡言、缺乏幽默感的人，但他仍然是帝国的忠实仆人，成功地团结了庞大的内务部。

During the Heresy, Pentasian fought against the attempts of Vethorel to try and promote the Mechanicum to Adeptus status, which would give them a formal seat on the Council of Terra. He reappeared during a Council meeting in the early stages of the Siege of Terra. By this time he had taken up drinking and despite having much of his powers stripped by Rogal Dorn's martial law still dutifully carried out his tasks around the clock.

在叛乱期间，彭塔西安反对维托雷尔试图将机械教提升为修会地位的企图，这将使他们在泰拉议会中获得正式席位。他在泰拉围城早期的一次议会会议上再次出现。此时，他已经开始饮酒，尽管罗格·多恩的军事管制剥夺了他的大部分权力，但他仍然尽职尽责地日以继夜地执行任务。

Pentasian survived the Heresy and became one of the members of the Grand Council of Reconstruction to rule the Imperium in the turbulent period of the Scouring. He was lobbied by Master of the Chosen of Malcador, Khalid Hassan, to assert the power of the High Lords of Terra as a counterbalance of the Primarchs, which he saw as dangerous given the events of the Heresy. He also demanded a seat on the Council, and these demands were dismissed by Pentasian as ludicrous. Pentasian went on to support Roboute Guilliman's plan to retake Luna, which may have just been a cynical ploy to reassert the Administratum's power by reacquiring its logistical and administrative network.

彭塔西安在叛乱中幸存下来，并成为重建大议会的成员之一，在大清洗的动荡时期统治帝国。他受到马卡多亲选的大师哈立德·哈桑的游说，肯定泰拉高领主的权力作为对原体的制衡，他认为鉴于叛乱事件，这是危险的。他还要求在议会获得一个席位，而这些要求被彭塔西安斥为荒谬。彭塔西安继续支持罗伯特·基里曼夺回月球的计划，这可能只是一个自私的策略，通过重新获得其后勤和行政网络来重申内务部的权力。

Pentasian came to view the Chosen as obsolete, and expressed his desire to seize their assets for himself during a meeting with Hassan. However this Hassan instead revealed itself as a Callidus Assassin, as he had become the new Grand Master of Assassins. Faced with death or compliance, Pentasian agreed to back down and ensured his cooperation as well as agreeing to give Hassan a seat on the Council.

彭塔西安认为亲选已经过时，并在与哈桑会面时表示希望为了自己夺取他们的资产。然而，这位哈桑却透露自己是卡利都司刺客，因为他已经成为了新的刺客大导师。面对死亡或顺从，彭塔西安同意让步，确保他的合作，并同意给哈桑一个议会席位。