The hypastistai are the elite infantry of the Makedonian and Seleukid armies, an elite versatile force capable of fighting in the traditional hoplite phalanx or as skilled swordsmen.

Elite
Hardy

Hail, Basileu! Before you stand your Hypaspistai: the elite of the elite and your personal guard. They are armed and armored in the finest equipment of the traditional hoplite: aspis, greaves, cuirass, helmet, spear, and sword. They are the best and richest of your men; far too worthy to risk in unwise actions. And yet they are without a doubt capable of multiplying the power of your army. Forming the right wing of the battle line or leading the assault on fortifications their heavy armor and weapons allow them to stand against even the hardiest of opponents and triumph with ease. They should be deployed where the fighting will be at its absolute thickest or nearby to fight with and to protect you.

Historically, the Hypaspistai (shield-bearers) first appear with Alexandros at the beginning of his reign as his elite troops and bodyguard. He used them extensively throughout his anabasis for special missions, assault of fortifications, and in support of light troops in rough terrain; however, details of the unit seem to disappear by the time Alexandros reaches India and remain as such until appearing in various sources for the three remaining Diadochoi kingdoms in different forms and perhaps briefly in Epeiros with Pyrrhos. Such examples of their deployment count them as possibly numbering a fifth of the 10,000 Arygraspides corps of the Seleukid kings or as the military police and closest guard of the Makedonian kings. Yet, despite their prowess, the Hypaspistai were either forced to evolve past the antiquated hoplite model as in the east or vanish with the fall of their kingdom as in the west.