A block cipher and AES candidate brought to you by IBM, based in part on the legacy of DES.

A movement from Gustav Holst's orchestral Planets Suite, subtitled Bringer of War. It features a lot of brass and it kicks butt. This is a favorite for large brass group arrangements.

Also, MARS is the virtual computer system that runs Redcode in the classic game Corewars.

Oh, and let's not forget the pulp fiction novels by Edgar Rice Burroughs.