Stone Shaman leader

[Xaladin]

This isn’t much of a theory, but we’ve seen each secret society so far led by or influenced by some Herald or Someone Important.

Skybreakers: Nale

Sons of Honor: Kalak

Ghostbloods: Thaidakar (Someone Important, bot just for being GB boss)

Diagram: King T

Veristatalians: ??

Evisagers??

We know hardly anything about the Stone Shamans, though Ishar might have to do with them.

So, who is it? I think we’ll find out in book 5.

Also, perhaps there is an actual Herald for each secret society? I believe there is a WOB that there are 9 secret societies. There could be one for each Herald sans Taln (though which Jezrien was involved with under this theory, beats me).

[Elegy]

It's possible that Ishar is involved, we'll see!

Some things:

The Veristitalians are not a secret society, although their members are mostly anonymous.

If there was a Herald involved with the Ghostbloods, Thaidakar wouldn't have tried to capture Kalak. If one of them is, the Ghostbloods themselves definitely don't know.

This is the WOB referenced that mentions 9 secret societies:

Quote

Aradel (paraphrased)

I asked Brandon just how many secret societies were on Roshar.

Brandon Sanderson (paraphrased)

There are nine currently working.

Words of Radiance release party (March 3, 2014)

But "on Roshar" is very vague. Considering all that we know, the Ire and the 17th Shard both qualify as "currently working" "on Roshar". It seems unlikely that those are involved with the Heralds, but who knows.

We also don't know if the Envisagers are included in that number, since there's no clear implication that they are still working - and now that the one character who was connected to them isn't part of the story anymore, it doesn't seem like it will turn out that they are. They also might have been a splinter group of the Sons of Honor, in which case they wouldn't be counted to begin with:

Quote

Hessi's Ward

Were the Sons of Honor a splinter group of the Envisagers?

Brandon Sanderson

RAFO, but let's just say you have the relationship backward.

YouTube Livestream 23 (Dec. 17, 2020)

So, hard to say at this point, but as of now, it seems unlikely to me that the Heralds and the secret societies add up (also because Shalash has shown no sign of being involved in one, but that could still be the case).

I can definitely see Ishar being involved in the Shin government though. After all, Szeth swore to fight it, and having Ishar on top of it makes for a good story for book 5.