Also, another note back on topic - I have to revise my earlier list to this new one:
The Chaos Gods
Malcador <---> Magnus (really up in the air here)
Eldrad (or equivilant in eldar farseers)
Grey Knight Terminators and the Grand Master
Tigurius <---> Mephiston <---> Ahriman (again, all hazy)
reason for my change is found on page 7 of the deamonhunters codex: paragraph 2 line 10. I'll sum it up by saying that the regular grey knights are ALL psykers and ae screened to include only the best. it also says that the best of them are the equal to the mighiest Librarians of the Adeptus Astartes (Tigurius, Mephiston, etc). It then goes on to say that among these grey knights there are those who excell and are made Terminators - obvious enough there... and from there they can be granted the rank of Grand Master, which it quotes as being "truly the greatest of the Emperor's servants" that statement seems to include even the Primarchs, as it is generally assumed that the Grey Knights are molded from the Emperor's own genetic material (geneseed).