G: I was poking around with basilisk and Medusa when I remembered gorgon (having not yet seen Pervinca's last comment), and thus
GORGOL the Butcher.
No idea about R; my knowledge of horses is very limited. I've tried working back from the theme, but I don't know what that is either.
'Graveyard' suggests 'people who died', but Annael doesn't seem to be recorded as dying, and Yavien only is by default (as a mortal). The others I think are significant for their deaths, but those two break my prospective theme and leave me floundering.
hS