- "Same principle as a condom. I'd rather have one and not need it, than need it and not have one."
- ―Rousseau, regarding her Beretta 84FS Cheetah (from Alien vs. Predator)
The Beretta 84FS Cheetah is a double-action, semi-automatic, magazine-fed, blowback-operated pistol chambered for the .380 ACP cartridge designed and manufactured by Fabbrica d'Armi Pietro Beretta.
Feeding from a 13-round staggered magazine, the 84FS features an open slide design, a frame-mounted manual safety with hammer decocking device and an anodized alloy frame with nickel-chromium-molybdenum steel barrel and hard chromed bore. The pistol's automatic firing pin block prevents the gun from firing in case of inadvertent drops or strikes against hard surfaces. The standard 84FS has a matte black finish, but a nickel-finished version is also available with plastic or wood grips.
- In Alien vs. Predator, Adele Rousseau carries a nickel-finished Beretta 84FS in a shoulder holster. In the Sacrificial Chamber, Rousseau draws the pistol, firing a single round before being subdued by a Facehugger.