The Immortal Guard of Imperial Iran, also known as Imperial Guard, was both the personal guard force of Mohammad Reza Pahlavi, the last Shah of Iran, and an elite combat branch of the Imperial Iranian Army. It was created in 1942 and disbanded in 1979 following the Iranian Revolution. It was named after the Immortals, an elite unit of 10,000 Persian soldiers in the army of the Achaemenid Empire.

Immortals or Persian Immortals was the name given by Herodotus to an elite heavy infantry unit of 10,000 soldiers in the army of the Achaemenid Empire. The unit served in a dual capacity through its role as imperial guard alongside its contribution to the ranks of the Persian Empire's standing army. While it primarily consisted of Persians, the Immortals force also included Medes and Elamites. Essential questions regarding the historic unit remain unanswered because authoritative sources are missing.