The name Athanatoi or Immortals derives from A-without, Thanatos-death. This name was and continues to be an effective means of causing fear and awe among people. Three different military units were called “Immortals”: the Sassanid Persian Zayedan cavalry regiment, the Achaemenid 10.000 elite warriors and the professional cavalry τάγμα of the “Byzantine Empire”. This post will focus on the latter. Fairly little is known about this elite unit, leaving space for some speculation. The Athanatoi were part of the τάγματα regiments, elite guard units that constituted the core of the “Byzantine” armies approximately from the 7th to the 10th AD. The Athanatoi were a body of heavy cavalry drawn from the Eastern Roman noble youths. Created by Emperor John I Tzimiskes, this unit was commended by a Δομεστικος , a military officer who was the descendant of the late Roman Protectores Domestici. The unit usually camped near Costantinople with the other elite τάγματα. The Athanatoi were probably equipped as heavy cataphracts, with mail armor or scale/lamellar armor (κλιβάνιον), a helmet, a long spear (κόντος), horse armor and a backup weapon.