Ash in Alien
Disguised as a human crew member, Ash's mission on board the Nostromo in Ridley Scott's 1979 film is not quite as it seems. Instead of working for the ship and its crew, Ash is secretly following orders from "the company", which wants to retrieve the alien for study at any price. Cue unpleasantness for all concerned, with most of the crew dead, Nostromo destroyed and Ash losing his head in an incident involving a fire extinguisher.
IT moral
Your suppliers may say they're here to help you, but how aligned are their missions with yours? Beware building your corporate IT around something that lies outside your control and cannot easily be replaced, if your vendors have a history of pushing solutions that work rather better for their bottom line than yours. Also, don't go chasing the office cat through the corridors late at night.
(Credit: 2003 Twentieth Century Fox)
Gary Numan?