Quotes: Sentry Gun

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.
Plan 7 of 9 from Outer Space