Ravagers

The Ravagers is a death cult dedicated to Gruumsh the Ruiner located across Dividing Plains.

Society
They are rumored to be ruled by four Slaughter Lords leading four main branches of the horde. However, no one outside its ranks knows who is really in charge, the long-term plans of the horde, or even if they exist. Ravagers are fanatically devoted to their deity, The Ruiner, who grants the lords blessings, artificially enhancing them before the battles, and provides them with magic powers, allowing them to cast several spells.

One branch of the Ravagers, led by the elf Kalydria Darkeye, has created a fort within the Bramblewood Forest. There they performed a ritual to transform the local giant spiders into demon-feed spiders. Another branch led by the half-elf/half-dragonborn Grud the Great is highly organized and instead worships Bane the Strife Emperor, and plans to march on the village of Turst Fields.

Behind the Scenes
In the Critical Role: Tal'Dorei Campaign Setting sourcebook, the Ravagers were overwhelmingly orcs and their goblin slaves, with other goblinoids also sometimes involved.

In the, Matthew Mercer discussed the process that led to the reconsideration of the how orcs and the marauders of Tal'Dorei were depicted:

There is still a brief reference to goblin Ravagers in the Explorer's Guide to Wildemount, but the sourcebook laid out a social, rather than inherited, explanation for some orcs' behavior. And in the Tal'Dorei Campaign Setting Reborn, moreover, the Ravagers have their roots in a goliath herd, are composed of people of many races like firbolgs and humans, and it is explicitly their "choices, not their ancestries," that make them evil.