A low-level thug used in a
fight mainly to increase numbers; an expendable no-name criminal; an unknown.
The concept of mooks is used in many action movies (particularly in kung-fu) and
beat-em-up arcade games, where the hero(es) cut through wave after wave of enemies easily (these being mooks) until they reach
the boss of the scene, who despite being possibly weaker-looking than the mooks, is usually much more powerful/elusive.
"Remember the Stormtroopers from
Star Wars? How hundreds of them couldn't
hit the broad side of a docking bay
door? What a bunch of mooks."