Marius Amalrich is a Marshal of the Black Templars. Commanding the Cruxis Crusade, he came to the aid of Imperial defenders on Cadia during the 13th Black Crusade. During the final actions of the battle for the Cadian System, Amalrich was among those seeking to protect Belisarius Cawl's artifact from the Black Legion. This team of defenders, including Saint Celestine and Inquisitor Greyfax, were ultimately saved by Eldar and guided into the Webway on Kalisus.
Amalrich was distrustful of his new Eldar "allies" but nonetheless was forced to accompany them to Macragge, where he aided in the fight to resurrect Roboute Guilliman in the Ultramar Campaign. Amalrich was the sole survivor of his Crusade after the battle at the Fortress of Hera, and took up the Black Sword in the aftermath. Later during the Terran Crusade Amalrich was captured by Chaos forces along with the rest of the Imperial expedition, but freed by Cypher and his Harlequin allies. The escapees came under renewed Chaos assault, and Amalrich gave his life to impale Skarbrand through the chest with the black sword. Guilliman was later able to exploit this wound to defeat the Bloodthirster.