Greel screamers were carnivorous, flying predators of the avian variety, and they are considered non-sentient. They were indigenous to the forests found on the planet called Pii IV. The name of this avian species comes from the loud sounds they make when their territory is threatened. They often lived in groups ranging from four to eight within greel trees. The physical characteristics of the greel screamer included a reptilian body that was 0.75 meters in length, a beak filled with teeth, and flexible wings that spanned 1.5 meters. Despite the Greel Wood Logging Corporation's attempts to scare away these aggressive avians from trees before felling them, greel screamer attacks still occurred during the logging process. This danger necessitated the assignment of workers to "crimson duty" to protect the other members of the crew.
During the time of the Galactic Civil War, a certain group of people joined a logging team employed by the Greel Wood Logging Corporation on Pii IV as a means of escaping the Imperial forces. While they were helping the logging crew, these individuals engaged in combat with greel screamers, successfully fighting them off.
The creatures known as greel screamers were first referenced in "The Greel Wood Haven," which was an article featured in the sixth issue of Star Wars Adventure Journal. This roleplaying magazine was published by West End Games in May of 1995 for their Star Wars: The Roleplaying Game. This article gave an adventure idea that was set on Pii IV, and it is assumed that the adventure played out as described in the article.
- " The Greel Wood Haven " — Star Wars Adventure Journal 6 (First mentioned)