I might be wrong but... I think I found the Predator in Avernum EfTP Not just any predator but The Predator (Yautja) from the movies. It's far to the utmost north, northwest of Fort Draco in the Aranea caves behind two secret doors / switches. When you enter the small room you find: "There is a skeleton hidden at the end of this passage. It's very old, and it's definitely not human. It's a tall, very thin humanoid with a huge skull. You've never seen a creature like this before, and the bones are so old that they're practically crumbling to dust before your eyes. Very strange."
This description in itself does not imply that it is a Predator but what you find next to the remains is a "Strange cloak: a shimmering, translucent cloak, made for someone very tall and thin. You've never seen fabric like this before" and six Razordisks: "A disk with a razor-edge, made for throwing. It doesn't look like any human-made blade you've vere seen."
What do you think, am I reading too much into it?