Adonalsium

The exact nature of Adonalsium has not yet been fully revealed. However, it is essentially the cosmere's power of creation that permeated and permeates everything.Reddit AMA 2013, 4/15/13
==History==
According to Brandon, Adonalsium’s power was original to Adonalsium. There was no predecessor to Adonalsium.DragonCon 2019, Atlanta, GA, 8/29/19
Pre-Shattering, Adonalsium intentionally prevented the spren from accessing Surges through fabrials and such. This was both a passive and an active action. Also according to Brandon, the way that Adonalsium worked was just the way that he saw the way the world (i.e., magic) worked. He didn't want the spren to be able to do that, so they couldn't.Starsight Release Party, Orem, UT, 11/26/19Book signing, American Fork, UT, 12/12/19
Long ago there was a plot to destroy Adonalsium. It failed.General Signed Books 2015, 1/1/15 However, some unknown time later, due to as yet unrevealed events, Adonalsium was killed and Shattered by the sixteen eventual Shardholders (and others in attendance),Book signing, Hoboken, NJ, 12/3/16 per the letter, the second letter, and from what Khriss said above.
Thus, Adonalsium was intentionally Shattered into sixteen pieces, known as Shards of Adonalsium or 'Shards' for short - which are pieces of the power of creation itself - and that they were then picked up by those sixteen now Shardholders.Book signing, Huntington Beach, CA, 3/5/1416 Shards
So, those who killed Adonalsium were a combined force, but a diverse group with equally diverse motives. Some wished for the power; others saw killing Adonalsium as the only good option left to them. Together they murdered a deity, and became divine themselves.Arcanum Unbounded, pg. 265
Rather than half-gods, they could be considered to be fractional gods. And gods with no particular qualifications for deityhood, other than being conniving enough to murder the guy who had the job before.Arcanum Unbounded, pg. 265
Also, it is not random which of the sixteen Holders got which Shard. And Shards very rarely change hands. However, the power distorts the Holder.Arcanum Unbounded, pg. 265
Further, Adonalsium created the first humans, so the gods of each cosmere world had a pattern to use.Arcanum Unbounded, pg. 265
There are other forces within the cosmere outside of those which have been derived from Adonalsium. One is a force that opposes Adonalsium (a force that still exists),Concious opposition and there are those who say that "subtle forces" are being made manifest, separate from Adonalsium.The Alloy of Law Annotations, 3/14/14
==Present Day==
Wit asks Dalinar if he‘s ever heard the term. Dalinar responds perplexed, having not quite understood the word, to which Wit replies "Nothing."
==Notes==
Hoid was, apparently, present at the event of the Shattering.Observer or instigator? Frost is also well aware of it.
Brandon often refers to Adonalsium as male in Q&As. He has not yet revealed why, when Shattered, Adonalsium split into both male and female Shards.
==Trivia==
Adonai is the Hebrew word for Lord. Israelites would often refer to God as Adonai to avoid using the name of God, Yahweh.Name of God
==Speculation==
While the sixteen people referenced above (and perhaps some others) were instrumental in the Shattering, it may have been Adonalsium’s own plan they were carrying out, whether they knew it or not.
However, if that theory is correct, it’s possible that Hoid is on the wrong end of things with whatever he’s trying to do, and that Frost is justified in admonishing Hoid (in the second letter) that they are like children stumbling around in the workshop, and may well do more harm than good. Then again, it’s just as likely that whatever Hoid is trying to do is exactly what Adonalsium expected and intended to be done.
Also possible is, a little theory still not proved by thereal.shadow, that Hoid himself - the man with the many names - is the remaining part of Adonalsium, just like the Stormfather - a very powerful spren - is the remaining part of Honor. Not like the other Shards, he isn't another person, he is the immortal part left from Adonalsium. That would also explain many things:
* The way and plans Hoid follows (he maybe just tries to let the gigantic plan from Adonalsium work out).
* On the question of Dalinar, Hoid responded that he's not a Shardholder. Also, he said that he had his own plans and stood on no one's side, and he would watch the world burn, with tears in his eyes, to get what he is there for. This means that first of all, he HAS the power to do so, while he isn't one of the direct gods of this world, which also means that he is powerful enough to avoid the others. Also, who else would gain anything from destroying another world, except somebody who could as easily create a new one?
Another reader has speculated that Adonalsium was Shattered by a Dawnshard.
==Q&A with Brandon==
Q: Are you ever going to do a big story about Adonalsium and take it out of the shadows?
A: Yes, um, the series called Dragonsteel itself is that, and then at the end of all of this, there will be kind of a climactic one. So eventually yes, it is just a little ways off.Dragonsteel
Q. You mention Adonalsium as a being, and that they were split. Where one supposedly supreme being exists, are there others?
A. That's a RAFO.Emerald City ComicCon 2018, Seattle, WA, 3/1/18
Q: Was Adonalsium shattered intentionally, and if so, was the intention malevolent?
A: Yes, and RAFO.Book signing, Huntington Beach, CA, 3/5/14
Q. I know that with Harmony, he has difficulty interacting because he holds two Shards. Did Adonalsium, since he had all these other personality traits, also have issues directly interfering? 
A. A RAFO! Good question. I've never been asked that question before.JordanCon 2018, Atlanta, GA, 4/20/18
Q. Does the fact that Adonalsium has ten letters in his name at all relate to the big magical number on Roshar?
A. No. Complete coincidence. Good question. Excellent question. I came up with the name years before. The name existed before I canonized Roshar as ten. The name existed when I was working on Dragonsteel, before I even had Roshar. Back when Dalinar existed, but Roshar didn't yet exist. The connection there is a just pure coincidence one. If I'd been really cool, it would have sixteen letters. And maybe, in their languages, it does.Dragonmount Zoom Call, 12/10/20
==References==
Category:Cosmere