Yeah, Primarchs would be a stretch. That being said, the Devs did allude to some named characters making an appearance. I would expect someone along the lines of Kharn or Abaddon rather than Angron and his peers, though.

1. Ahriman the Exile
2. Lucius the Eternal
3. Honsou of the Iron Warriors
4. Talos the Soul Hunter
5. Abaddon

Argel Tal
Angron
Talos
Kharn
Fulgrim/Konrad/Magnus.. All have such great and sad stories.

Does Talos, or really any Night Lord, count as a "Chaos" character? Well, REAL Night Lords that is. No true son of Kurze would shame themselves by stooping to warp taint. If so, Talos is my favorite.

Whoever leads the Death Shadows

1. Kaleb Daark (First Wielder of the Dreadaxe)
2. Sarpedon (Chapter Master Soul Drinkers)
3. Kathel (Chapter Master of the Sons of Malice)
4. Angron (Nuff Said)
5. Kharn the Betrayer (Nuff Said)

Kharn
Sevetar
Argel tal
Talos
Curze

kathal the anarch(chaos lord) of the sons of malice

The 5 Gods of Chaos:
1-KHORNE
2-Nurgle
3-Tzeench
4-Slaneesh
Mysterious number yet to be discovered-Malal

The one and only:


Ahzek Ahriman!