I think its a little weird how there are "Traitor" chapters and "Renegade" chapters, if both seem to all worship Chaos. Do renegade chapters exist that do not follow Chaos at all? If not, I'm curious why there is the distinction between the two. (Other than "when did they turn against the Imperium?")

For some reason I seem to remember one chapter that doesnt, and just kinda shows up to Imperial planets to help them even if the planet doesnt want their help, but I cant recall the name so dont know if they exist or if I imagined that xD

All chaos chapter follow either one god or chaos undivided and the GW I don't know why call our tactical guys traitor it's just not right

a "renegade" chapter is always an heretic and traitor but is not always a chaos worshipper.

Yep, I'm Traumkampfer, the renegade who was immortalized by Warmaster Nathan's strange fascination with my name xD

I'd like to imagine there are some renegade chapters who were simply misunderstood (like my Sons of Malice in the beginning), but the wiki groups both Renegades and Traitors together into a massive list, so that would be a lot of lore digging to find one if they exist D:

There are only a few exceptions which have ever been put into fiction, and most of those have been short-lived. Dead Sky, Black Sun did feature a group of renegades who were simply not loyal to the Imperium, but they were only alive thanks to certain specific situations.

The only few exceptions who survive I do personally know of largely exist by serving as muscle for other groups. These are usually renegade Inquisitors or Rogue Traders, the sorts of people who can continue to supply them with the arms and armour they need to remain operational. Even then however, they do tend to only exist on demi-company levels or simply as indivuduals.

No, not all renegade chapters worship chaos. There used to be a few that stayed as pirate groups, red corsairs for example were once a pirate group before they fleshed-out the badab incident.

Also not every "Traitor" Legion worships chaos, Nightlords Alpha legion and Iron Warriors see chaos very differently from Black Legion and Word Bearers.

Generally the difference between Traitor and renegade is upto the person doing the writing as there are cases for both being used in each place, but its mostly successor chapters that go rogue =renegade, legions that turned on the emperor = traitor.

Soul Drinkers come to mind. Knights of Blood too.

@Daemonkin
Eh...Alpha Legion and Iron Warriors are almost always classed as undivided. They praise all gods equally and seek commonality with all chaos. hell Perturabo is a daemon prince But yes, they all do see it differently than others...but for the most part its about praising the gods equally, not just one.

@Traumkampfer
in "modern" 40k almost no real 'renegades' exist. Although I bet a few rogues dabbles here and there. Generally almost all the renegades eventually fall to status of heretic/traitor at some point or another. Cypher is one of the more well known 'renegades' although hes also classed as a traitor. That and his rather strange power of never dying is another thing entirely

Crimson Slaughter is a good example between Traitor legions who fell during Horus Heresy and renegades that slowly corrupted after the civil war. Then know as a Crimson Sabers they were the most loyal and followed Codex Astarters fanatically, but this turned out to be the ultimate downfall of that chapter.

In their fanatical pursuit to clear heresy from the galaxy they slaughtered a whole planets population and from this whole chapter was cursed by Khorne, which manifested in voices of the slaughtered and only more killing would silence the voices for a while.

As the Inquisition found out what the chapter had done they were declared Excommunicate Traitoris, which meant that the chapter was declared as renegades and for the loyal marines at Crimson Sabers death would be better alternative, so they embarked on a suicide mission in to the Eye Of Terror, but when they emerged back from Immaterium Crimson Sabers were no more, only a renegade warband of slaughter driven lunatics who continue kill to silence the voices.