Renegade Marine chapters are really few and far between.
I believe the Marines Errant may be one of them... otherwise, you're gonna end up in the Eye o' Terror and need that bolt round through the head anyway.
Although the majority of the renegade chapters are chaos marines and turned to chaos, not all have done so and are merely renegade out of difference of believes (For example not believing in the god emperor) or heretical acts (joining forces with another faction or such). And that I find very interesting. I'd love to have a chapter that is renegade but human and gains their support from say... Eldar or Tau forces. (I mean, both of them could easily help Space Marines if their goals are the same, Space Marines are mostly the ones that 'deny' them for being xenos after all).
There are a few, of the top of my head:
Of course the Soul Drinkers. I suggest looking them up. Great example. Their ideology is based around the idea that the Imperium has betrayed everything the Emperor stood for - to which I would really agree from a lore standpoint - You know what... look here: http://wh40k.lexican...i/Soul_Drinkers I read this a long time ago when I looked into Warhammer 40.000 Lore. I think this is really interesting myself.
Relictors, became a renegade for the use of chaos weaponry (Not being actual chaos). They believe in trying to use the dark weaponry against itself.
Apocalypse Company (Doubtful I believe, either regular Renegade or Chaos)
And others. Although they are in few, yes, I find them more interesting than most Space Marine and Chaos Marine chapters. So... Soul Drinker Techmarine please?
Edited by Caescen, 07 December 2009 - 12:42 PM.