The short description of Pacific Rim says it “chronicles the battle between giant alien monsters who invade our world and the enormous robots — called Jaegers — which humans build and pilot to defeat the alien threat.”
Seeing the word “Jaegers” immediately made me think of Cordwainer Smith, whose fictional manshonyaggers feature in several stories, referring to the war machines that prey on all men except for those they can identify as Germans. The word is compounded from the German words menschen, people, and jäger, hunter.
In “Mark Elf” the wise Middle-Size Bear, the sort of character Smith would later term one of the underpeople, reveals the mystery behind the neologism:
Said the bear in perfect German, “… You have stopped a Menschenjäger very mysteriously. For the first time in my own life I can see into a German mind and see that the word manshonyagger should really be Menschenjäger, a hunter of men.”
Manshonyaggers (spelled various ways) also appear in “Scanners Live in Vain” and “Queen of the Afternoon.”
Other sf writers than Smith have called things or named characters jäger, some under the influence of German military terminology. Del Toro should be free to do the same, I just thought it was an interesting coincidence.