Myrmidon

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Greek Mythology A member of a warlike Thessalian people who were ruled by Achilles and followed him on the expedition against Troy.
• noun A faithful follower who carries out orders without question.

from The Century Dictionary.

• noun One of a warlike ancient Greek people of Phthiotis in Thessaly, over whom, according to the legend, Achilles ruled, and who accompanied him to Troy.
• noun [lowercase] A devoted and unquestioning or unscrupulous follower; one who executes without scruple his master's commands.

from the GNU version of the Collaborative International Dictionary of English.

• noun One of a fierce tribe or troop who accompanied Achilles, their king, to the Trojan war.
• noun A soldier or a subordinate civil officer who executes cruel orders of a superior without protest or pity; -- sometimes applied to bailiffs, constables, etc.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• proper noun One of a fierce tribe or troop who accompanied Achilles, their king, to the Trojan war.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun (Greek mythology) a member of the warriors who followed Achilles on the expedition against Troy
• noun a follower who carries out orders without question