The "River Ghost" is a sapient alien creature encountered on the "Game Preserve Planet". It's fair to assume that members of its species have been abducted by the Yautja and brought to that world to be hunted.
This alien species is a bipedal humanoid with a complex exoskeleton and is noted for its amazing speed and agility. They also seem to have small insect-like creatures living on their skin, possibly as symbionts.
- Predators (2010)
- The name "River Ghost" isn't used on the film and actually comes from an earlier version of the script, where the creature was briefly spotted in the vicinity of a river, almost like an apparition.