Unsullied

The Unsullied are elite warrior-eunuchs bred and trained in Astapor, one of the three major cities of Slaver's Bay. They are slave-soldiers famed for their skills and discipline in battle. They are also often purchased from Astapor by some of the Free Cities, such as Qohor.
Unsullied battle tactics are based on the legions of the old Ghiscari Empire, involving large groups of them fighting in lock-step phalanxes using spear and shield, though they are also trained to use shortswords for close-quarters combat. Slave-eunuchs who have been trained from birth to fight, the Unsullied are renowned for their utter discipline on the battlefield, both in their usage of incredibly coordinated large unit phalanx formations, and because they will never break in the face of overwhelming odds, even to the point of death.

Because they are eunuchs, the Unsullied will not succumb to bloodthirsty or sexual urges in the midst of battle; their actions will only go as far as what they have been ordered to do, and nothing more. The Unsullied also seem resistant and even immune to pain[1]. However, Unsullied do possess emotions and can show anger.