(Feel free to speak up if I leave anyone out)
The Cabal: Claim to want to defeat Chaos by helping Horus win the Heresy.
Erebus: Intends to bring about the ascendancy of Chaos by winning the Heresy.
Alpharius/Omegon: One's working to help Horus, the other is secretly pro Emperor. Or possibly the other way around. Might be working with the Cabal. Or not.
Ollanus Pious: A Perpetual, heading towards Terra through space and time with a mysterious ritual knife. Seems to be planning on helping Emps in the battle with Horus. SEEMS.
Damon Prytanis: Perpetual. Rescued the revived Cyrene from Lorgar's flagship. Motives and allegiance unknown.
Malcador: the Sigilite. Moving pawns on the chessboard to arrange a victory over Chaos.
Lorgar Aurelian: Primarch of the Word Bearers. Working to win the Heresy. Maybe. Manipulated Angron, interaction with Horus in Betrayer suggests he's up to something.
Roboute Guilliman: Primarch of the Ultramarines. Wants the Imperium to survive, Lorgar's head on a spike. Recruited Iron Hands and loyalist Iron Warriors for his plans. More details forthcoming in Unremembered Empire.
Unknown: Faceless figure who met with the witch who helped Erebus turn Horus on Davin. Could be any of the above except Erebus in disguise.
Edited by Wade Garrett, 08 September 2013 - 02:21 AM.