Void Bringers
A Chapter of dubious canonicity created by a little Duncan Rhodes, with nothing to their history but a cool-ass name, some Iron Warriors stripes on their shoulder pads.
The only thing of any significance to note about them is that one of the Chapter's Tactical Marines was Duncan's first painted miniature. He keeps it next to his painting desk, to remind him on how many coats to use, and has since painted a Primaris version of the same Marine.
Gallery
File:OneThickCoat.jpg|Before learning the wonders of two thin coats and thinning paints... he made this. File:Duncan-evolution.jpg|Changes and progress very rarely are gifts from above. They come out of struggles from below.