Sebastian Yarrick, the "Hero of Hades Hive," is a Commissar of the Officio Prefectus, famous for his involvement in the Second and Third Wars for Armageddon in the last century of the 41st Millennium.

It was during a brutal hand-to-hand duel with the hulking Warboss Ugulhard in the final battle for Hades Hive that Yarrick lost an arm. He took the Ork's head in return, replacing his severed limb with Ugulhard's own Power Klaw.