Alexia Ciannor was the protagonist of the RPG supplement, the Withfire Trilogy, which ended up giving birth to the Warmachine game world.
Butcher, Beast-09, and the Behemoth represent the brutal melee combat options for Khador. The Butcher goes mad over the course of the story, hardly recognizing the difference between friend and foe as he charges with his mighty axe, Lola. Beast-09 and the Behemoth are character warjacks that can tear things up in defense of the Motherland.
Coleman Stryker and Cygnar
Cygnar is the protagonist faction of Warmachine and the Jewel of the Iron Kingdoms, and Coleman Stryker is the posterchild for the reign of its current ruler, King Leto.
Deneghra, the Deathjack and the Deathripper
The magical power of Cryx is inherent in these three. Deneghra is a warcaster who controls the shadows, the Deathjack is the helljack who imitates the spellcasting of Cryxian warcaster, and the lowly Deathripper is a fast moving bonejack who can deliver magic via its arc node.
The Mage Hunter of Ios operates as a Mercenary gathering information about the spellcasters she seeks to assassinate. Her specialized skills are anti-magical in nature as she seeks to eliminate those she feels responsible for the waning of the Elves.
Gorten Grundback was the first Rhulic warcaster included in the game. See R.
Harbinger and Hierarch
A girl in the Protectorate of Menoth has been responsible for speaking on behalf of Menoth to the Hierarch of the Menoth faith. When one Hierarch fell by the gates of Caspia, she, the Harbinger of Menoth, chose his successor.
Journeyman Warcaster, aka Junior. Before Cygnar's warcasters become fully fledged warcasters, they must apprentice in the field under the auspices of an active warcasters.
Kreoss and Kaelyssa
Though Kreoss is a Menite warcaster and Kaelyssa is a Retribution warcaster, both have certain anti-magical protections such as spells and abilities that eliminate or reduce the effectiveness of magic.
Menoth and Morrow.
These two gods hold sway over two of the Iron Kingdoms. Menoth the Lawgiver is an active force in the Protectorate of Menoth and some of Khador, whereas Morrow is the chosen god of the people of Cygnar.
Old Witch and the Orgoth
These old forces continue to impact the Iron Kingdoms. The Old Witch, who once fought the Orgoth, is a force who may be the representation of Khador itself. And Orgoth remains litter the Iron Kingdoms with their burial sites and the Fell Blades of the Doom Reavers that still exude a destructive evil magic.
Page 5, Play like you have a pair. The motto of the game since the release of Warmachine: Prime.
Queen Skarre of the Broken Coasts runs the Black Fleet after Terminus left it in her charge. She uses blood magic to see and manipulate the Seas of Fate; more importantly, she has a 'Great Rack'.
Rhul is one of the few kingdoms not actively waging war. Instead, being Dwarven archetypes, they hire out as mercenaries for other factions and develop excavation and mining 'jacks that can be weaponized for battle.
Steelhead Company of Ternon Crag is the largest and most organized mercenary company of the Iron Kingdoms. Their clients include the Llael resistance fighters such as Ashlynn d'Elys, and the Cygnaran traitor, Asheth Magnus.
Toruk, Terminus, Tartarus and Thralls- The Dragonfather Toruk created Cryx, raised Terminus to be one of his Lich Lords, Bane Lord Tartarus creates more Banes from beyond the gate, and Thralls make up the large portion of the Cryxian armies. Mechanithralls, Bile Thralls, Bane Thralls...
The afterlife in which the War of Souls is raged, Urcaen is a shadowy landscape through which few of the living (those on Caen) can travel and return. The Testament of Menoth found the Omegus in these lands, and brought it back with him to Caen, along with the ability to open the door and travel through it.
Vinter Raelthorne the IV
The former king of Cygnar, Vinter commands the loyalty of traitors such as Magnus the Warlord and the Skorne up until the events of Hordes: Metamorphosis.
Xenophobia kept the Elves of Ios within their borders until it came to pass that one of their gods was captured.