The Collared are the up and coming thieves guild within Thyre. With all the misery and destruction of the shadow war between Nobles and The Axeman there are plenty of viable targets. Especially, when one side pays for something to happen to the other.
There are rumors about who is running The Collared, but no one could say for sure.
By no means as great as other noted thieves guilds like The Merchants Below or The Cutters but it is finding it’s own place within Thyre.