Most powerful/influential Chapter

[Cap'nSmurfs]

The Ultramarines are the ancestors of two thirds of the Imperial Space Marines. Out of roughly one million extant Space Marines, six hundred and sixty thousand are direct descendants of the Ultramarines Legion and its heroes. All of those, to one extent or another, venerate the Codex Astartes as their guiding light. Even Chapters formed from other Legion stock do so, with some notable exceptions.

If you're talking about "influence", the Ultramarines can't be beat. Their close ties with a great many of those descendant chapters make them a terrifying proposition if they start calling in favours, too.

[Denzark]

Power - Ultramarines. For all the reasosn already given.

Influence a different matter.

I think Dante and the BA are at an interesting point. I think BA were seen as a double edged sword by Imperial allies, due to some of their more...dubious... practises. That said, Armageddon represents a changing of opionions whereby their reputation is backing towards heroic again.

Similarly, the Codex Fluff for Logan Grimnar makes him out to be one of the Imperium's most widely known heroes, even outside of Fenris. Again Armagedon and his actions afterwards make him popular to the common man - as opposed to a scary chapter that would turn up and be contemptuous of them.

I would say the fact that Grimnar is allowed to ignore Adeptus Terra dictates even to the stage of open combat against other imperial formations, based purely on what he thinks is morally right, shows how influential he is. After all this and the canis helix mutation would give sufficient cassus belli to call them traitoris. The fact that this isn't happen, and Fenris is a de facto closed system, leads me to call SW highly influential.

[Kaptain Badrukk]

Minotaurs: If I'm correct, isn't it hinted that they basically work with the Inquisition.

Nope. It's flat out stated that they work directly for the High Lords of Terra.
When it comes to munitions and equipment they are second only to the Salamanders (although IHands, Bangels and a few others are hotly contesting that spot).
They re-grow their numbers with terrifying ease, due to a gene-seed quota direct from Terra herself and sanction practices hinted at in their FW fluff which suggest that they do so in slightly dodgy accelerated ways.
They're a fleet based chapter whose exact size and location are generally unknown, esp after badab where they looted traitor ships.
A lot of other chapters downright worry about (the closest a marine can get to fear) what would happen to them if they were on the sharp end of their wrath. So they have fear factor 11.
They PERSONALLY may not wield much political sway, but the guys they answer to run mankind.
All of that aside they're likely outnumbered at least 3 to one by the Black Templars. So if it ever came to 1 on 1 fisticuffs they'd top about every other chapter but them.
Once getting your successors involved comes into play the Ultras win hands down.
BUT with the High Lords backing them I'd say they're they most influential overall, if only by vestige of association.
Ultras are clearly the most so on their own. But Bangels and Swolves are very close behind.

However since the Minotaurs almost always with the express sanction of, or on the behest of, the High Lords. That means they bring with them the potential alliance of every "loyal" marine chapter and the entire imperial war machine. Which is frankly overpowering for even the Ultras (as I'm sure some of their successors would either turn on them or sit on the fence).
But none of them would like doing it.

I'm plugging for Minotaurs.

[daboarder]

Power - Ultramarines. For all the reasosn already given.

Influence a different matter.

I think Dante and the BA are at an interesting point. I think BA were seen as a double edged sword by Imperial allies, due to some of their more...dubious... practises. That said, Armageddon represents a changing of opionions whereby their reputation is backing towards heroic again.

Similarly, the Codex Fluff for Logan Grimnar makes him out to be one of the Imperium's most widely known heroes, even outside of Fenris. Again Armagedon and his actions afterwards make him popular to the common man - as opposed to a scary chapter that would turn up and be contemptuous of them.

I would say the fact that Grimnar is allowed to ignore Adeptus Terra dictates even to the stage of open combat against other imperial formations, based purely on what he thinks is morally right, shows how influential he is. After all this and the canis helix mutation would give sufficient cassus belli to call them traitoris. The fact that this isn't happen, and Fenris is a de facto closed system, leads me to call SW highly influential.

thing is most of the imperium doesn't know about the red thirst and the black rage, the BA's and their successors go to huge lengths (having squeeky clean geneseed for tithing) to prevent anyone form knowing that.

To be fair though there are "rumours" and "heresay"

as to the ultras, the thing is that to a lot of their successors loyalty to ultramar isn't really a thing, they took guillimans teachings to heart adn sepparated all ties, whereas chapters like the blood angels and dark angels have very strong ties to their successors due to their mutual secrets and teh like.

[Cap'nSmurfs]

This is a hard discussion to have without defining "power" and "influence".

[Katharon]

Everything's relative.

[dark messenger]

I'd have to throw my vote in for the Wolves of Fenris.
Due to the actions and reputations of the last two Great Wolves, Ulrik Grimfang and Logan Grimnar, and the fact that Russ very sneakily didn't quite divide his Legion... If full strength were gathered at one place, they'd be able to bootstomp almost anything.
In terms of both power and influence as a First Founding Chapter and just how bloody dangerous they are the Wolves would match just about anybody in the Imperium.

Many of the other First Founding Chapters can also claim illustrious histories and great power too, but isn't the whole point of Guilliman's Codex that no one body of authority in the Imperium ever be strong enough to overpower and take charge?

[Demonicsarge55]

Oddly enough, I am going to throw the Salamanders hat into the ring. They are still a Legion, Vulkan did not agree with Guilliman's sorting of the Chapters and demanded that his Legion remained untouched, and it has.
They have no known Successors (though some are hinted at) and no one knows how many they are.
They also have one of the most elite 1st Companies in existance, the Fire Drakes, who are ridiculously well-trained, and have the best equipment available.
Let us also not forget the Artifacts of Vulkan, one of which is a SPACE LASER.
Speaking of equipment, lots of master crafted items, the finest forged weapons known to the Imperium.
Influence, these guys have tonnes of it, due to their humanitarian ways, they are famous for saving lives, and the Imperium loves them for it.

They dont have any successors because of the drop site massacre left them absolutely shattered.

[Dalleron]

If you are a humble human in the vastness of the Imperium, the most influential/powerful SM chapter would have to be the one that is in your sector at any given moment. Only when there are multiple chapters in system does it become a "weiner measuring contest". Then who's the boss probably comes from some
convoluted system set about in the Codex Astartes.

I imagine that the first founding loyalists would have more pull outside of their territories, by virtue of their chapter.

[DrLove42]

The most influential chapter of them all?

Well if you define influence as having the biggest effect on the others and the universe around them....

The Word Bearers. Ok technically a legion but shush.

The Word Bearers were first to fall, caused the fall of others and began the Heresy in the beginning. Without them the entire universe would likely have been a significantly different place