I always wondered who was the grey Knights progenitors. I dont means the Primarchs.
The codex said that malcador presented to the Emperor 8 uncoruptable individuals who was first captains of theat chapter.
Rumor mils said that they were from traitor legions who proved themseves uncoruptable
let gues who they were:
We can bet on Garoo (Death Guard) who was one of the first Inquisitive tipes Melcador remarked about.
Who else
I would put Locken (I know that he died at Istvan - but Dan Abnet in one of its commentary/interviews said that we can expect the return of Locken)
Iacton Qruze
Tylos Rubio
Whonder who next.