The Gorlan were silicate-based humanoids known primarily for the Gorlan Civil War, in which there were billions of casualties. When no-time spread across the universe, the Master took control of the Gorlan under the alias "General Malgrove," the Gorlan word for "Master." (AUDIO: The Two Masters)
Although the Vashta Nerada could not feed on silicon lifeforms like the Gorlan, they were still able to tear them apart. (AUDIO: Night of the Vashta Nerada)
In the 41st century, George Sheldrake employed Gorlans as his security service. (AUDIO: Buying Time)
Behind the scenes
Gorlan is also the name of a species in the Star Trek universe, mentioned only in the episode Mirror, Mirror.