"Apparently benign alien emissaries show mankind how to end the misery
of war, plague and famine. The Kanamits, nine-foot tall aliens, arrive on
Earth with one lofty goal: To Serve Man. They end war, they end famine.
They make the military wonder: what's the catch?"
Loved that episode: To Serve Man. Goes along with my repeated comment that when the aliens get here they will eat the fat ones first.