Sergeant Aldo Crowley was a member of the United States Colonial Marine Corps. He was a member of the USCM security detail stationed at Hadley's Hope on Acheron in 2179. He was subsequently involved in combating the Xenomorph infestation at the colony.
Crowley fell victim to the Xenomorphs when they finally overran the colony, either perishing outright or being captured and taken to the Hive for impregnation.
- In the audio drama adaptation of Alien: River of Pain, Crowley's rank is given as Private, yet in the novel he is a Sergeant.