What was the name of Alexander's childhood friend and companion?

Alexander’s childhood friend and companion was Hephaestion. The two were raised in the Macedonian royal environment and remained exceptionally close from youth through Alexander’s conquest of the Persian Empire.

Hephaestion was the son of Amyntor and probably belonged to the Macedonian nobility. He may have studied alongside Alexander at Mieza under Aristotle, although the surviving evidence about his early education is incomplete. Their friendship endured through court politics, military campaigns, and the pressures of ruling a growing empire.

Hephaestion was far more than a personal companion. He served as a bodyguard, cavalry commander, diplomat, engineer, and senior military officer. Alexander repeatedly trusted him with independent commands and important negotiations. By 324 BCE, Hephaestion had become chiliarch, effectively Alexander’s second-in-command, and married Drypetis, a daughter of Darius III.

Ancient writers compared the pair with Achilles and Patroclus. Some modern historians argue that their relationship may also have been romantic, but the safest historical description is that Hephaestion was Alexander’s closest friend, companion, and trusted lieutenant.