Space Marine Chaplains are the spiritual leaders of the Space Marines. They accompany their battlebrothers to war, chanting liturgies and pushing them to further feats of bravery. They wear black power armour and the deaths head mask, bordering on some Chaos Space Marine symbols. They enjoy warfare and the slaughter of their enemies, as they believe it to be the best way to honour the Emperor and their founding primarch.
They differ in their preaching compared to the Ecclesiarchy by their belief that the Emperor is not a god, just an inspired man. This is more how Space Marines see the Emperor.
Chaplains are often blessed with a rosarius from the Ecclesiarchy to symbolise the tenuous link between the groups. This device can protect the wearer from even a lascannon shot.
Within a Chapter
Chaplains feature heavily in a Space Marine's daily life. They also watch over the neophites, newly joined members of the Space Marines, waiting for their implants. They are notoriously strict and fiery but they are also known for sense of duty and responsibility for the brother marines.
Within the Fortress Monastery is the Reclusium, the place where the chapters holy relics and, sometimes, the body of their primarch, is housed. The Chaplains lead their sermons from here, and rouse the Marines in their love of the Emperor. The battle barges and ships of the chapters fleet also include huge cathedrals in the heart of each ship, allowing the Space Marines to pray while away from the fortress. They always lead the Space Marines in prayer, but a chaplain is not always needed for a marine to pray.
Armour
The armour worn by Chaplains are holy in themselves. Often, they are hundreds, if not thousands, of years old. It is frequently adorned with ancient pieces of equipment, making them waking shrines in and of themselves. The face plate almost always represents a skull, inspiring fear in their enemies and faith in their fellow marines.
He also carries the Crozius Arcanum, used in official ceremonies and worship, and is often topped with an Imperial Eagle or winged skull. It incorporates a potent energy field, allowing it to punch through armour easily.
Chapter Variations
Many chapters follow the Codex Astartes, but some have strayed from it. The Dark Angels use Interrogator Chaplains, forcing the fallen of their forces to confess and repent or to kill them after days of agonising pain.
The Iron Hands Chaplains are actually their Techmarines as well, as their link with technology is so strong.
In the Blood Angels chapter, the Chaplains lead the Death Company to their demise. They also care for those who completely succumb to the Red Thirst, keeping them locked on their homeworld, Baal.
Within the Space Wolves, the Wolf Priests fullfill both Chaplain and Apothecary roles.