"This next test involves turrets. You remember them, right? They're the pale spherical things full of bullets. Oh, wait. That's you in five seconds. Good luck."
— GlaDOS, Portal 2
Lonzak fumbled for a button on his commbelt. The door rolled open and the autosentries swung their liquid helium-cooled gunbarrels into a neutral position.
The Brigadier: Of all the cheek. They've got troops there!
The Doctor: I don't think so, Brigadier. Automated machine gun nest, I fancy; activated by body heat when you get within range.
— Doctor Who, "Robot"
In the service tunnel that connected the buildings of the colony to the processing station and each other, a pair of robot guns sat silently, their motion scanners alert and humming. C gun surveyed the empty corridor, its ARMED light flashing green. Through a hole in the ceiling at the far end of the passageway, fog swirled in. Water condensed on bare metal walls and dripped to the floor. The gun did not fire on the falling drops. It was smarter, more selective than that, able to distinguish between harmless natural phenomena and inimical movement. The water made no attempt to advance, and so the weapon held its fire, waiting patiently for something to kill.
— Aliens by Alan Dean Foster
"An automated ally for shootouts. The singularity's coming, so enjoy friendly robots while you can!"
—Sentry Turret description, PAYDAY 3
