Biographical information
Gender Male
Status Dead
Abilities Surgebinder
Occupation Knight Radiant
Appears in Words of Radiance (mentioned)

Kazilah is obviously a historical person in The Stormlight Archive. Presumed to be male given 'his' name, 'he' was a member of the Knights Radiant, likely from the time before they disappeared from amongst the population. 'He' is mentioned only in the Epigraph for Words of Radiance: Chapter 51. It seems 'he' turned traitor and was slain for 'his' betrayal.

In short, if any presume Kazilah to be innocent, you must look at the facts and deny them in their entirety; to say that the Radiants were destitute of integrity for this execution of one of their own, one who had obviously fraternized with the unwholesome elements, indicates the most slothful of reasoning; for the enemy's baleful influence demanded vigilance on all occasions, of war and peace.

–From Words of Radiance, chapter 32, page 17[1]