Black Templar Requiliarch
A design I did early last year to fill in for the Black Templar’s lack of Librarians. The Requiliarchs operate as their stand-in record keepers, but functionally would be more like a cross between a chapter artificer and a upper HQ level standard-bearer. So, still no psyker abilities. I imagine them often being some of the eldest of the chapter, other than dreadnoughts, hence the somewhat stooped pose (for a Space Marine). In terms of preexisting lore, I guess it could make a nice design for a Master of Relics too.
