Space Marine Chaplains are the spiritual leaders of Space Marine Chapters.
Warrior-priests, they fight alongside their battle-brothers, chanting the Chapter's sacred battle creeds, and inspiring their brethren to greater feats of bravery. To enemies they appear as terrifying and sinister figures in black power armour and skull-visaged helmets.
During the Great Crusade, the Emperor specifically outlawed religious worship of any kind, but several Space Marine Legions still employed spiritual advisors of some kind. The first known Space Marines who bore a resemblance to Chaplains were members of the XVIIth Legion, known as the Imperial Heralds. The Legion's 'heralds' wore black armour with a skull-faced helmet and a winged mace and delivered the Emperor's ultimatum to new worlds: submission or destruction.
