Watchers in the Dark
Watchers in the Dark are a diminutive robed2 race of creatures which inhabit the Rock, the mobile fortress-monastery of the Dark Angels Space Marine Chapter. They watch over the body of the Dark Angel Primarch Lion El'Jonson within a secret chamber at the core of the Rock. They are semi-unique as they possess a near exclusive ability to resist the warp and other magical entities, a trait which is shared with the rare and mysterious Pariahs who completely nullify the warp around them.
These silent creatures have been known to carry Dark Angels weapons to battle, and seem to be immune to all acts of violence. Dark angels accompanied by them are destined to greatness, but they will never give direct aid in battle.2