Source : Webster's Revised Unabridged Dictionary (1913)

Myrmidon \Myr"mi*don\, n. [L. Myrmidones, Gr. ?, pl.]
   1. One of a fierce tribe or troop who accompained Achilles,
      their king, to the Trojan war.

   2. A soldier or a subordinate civil officer who executes
      cruel orders of a superior without protest or pity; --
      sometimes applied to bailiffs, constables, etc.
      --Thackeray.

            With unabated ardor the vindictive man of law and
            his myrmidons pressed forward.        --W. H.
                                                  Ainsworth.

Source : WordNet®

myrmidon
     n 1: a follower who carries out orders without question
     2: (Greek mythology) a member of the warriors who followed
        Achilles on the expedition against Troy
     [also: {myrmidones} (pl)]