The Lockheed publicity was that was the nickname the Germans had for the P-38 although that doesn't appear to actually be true. German aces thought the rather sluggish early models of the P-38 one of the easier USAAF fighters to knock down.
The Japanese sometimes referred to it as 'silent death' because thanks to its exhaust passing through turbosuperchargers, it was a very quiet airplane.
The first Japanese home defense fighters that went up against the P-38 thought they were intercepting an unmaneuverable bomber, and got a rude surprise.