Buyard Cholik is a villain in the novel The Black Road.
In the book, Buyard is a former or corrupt Zakarum priest who summons the demon Kabraxis. His failing age and the toll of spell casting on his body drove Buyard to an insatiable hunger for power. Because of his hunger for power like any other corrupt priest, he turns to the dark side of magic, and resorts to demonology. Buyard Cholik starts a church in which he preaches about the black road and the many miracles it performs. In truth, it consumes souls in return for the miracles.
Buyard is the host of Kabraxis for the remainder of the story until he/they are slain by Darrick Lang. Kabraxis, in part, lives on as a voice in Darrick's head, and as the source of some power for Darrick. However, Buyard is, apparently, completely dead as his body was Kabraxis' vessel.
This death makes his appearance in Diablo III highly unlikely, although possible. If Darrick or Kabraxis make an appearance, or if plot from the Black Road is discussed at any point, he may also be mentioned without actually appearing.