Alexander III of Macedon, commonly known as Alexander the Great, was a king of the ancient Greek kingdom of Macedon and a member of the Argead dynasty. He was born in Pella in 356 B.C.E. and succeeded his father, Philip II, to the throne at the age of twenty. He spent most of his ruling years waging an unprecedented military campaign through Asia and northeast Africa, and he created one of the largest land empires of the ancient world by the age of thirty, stretching from Greece to northwestern India. He was undefeated in battle and is widely considered one of history's most successful military commanders. 

Alexander became legendary as a classical hero in the mold of Achilles (from whom he and others claimed he was descended), and he features prominently in the history and mythic traditions of both Greek and non-Greek cultures. He became the measure against which military leaders compared themselves, and military academies throughout the world still teach his tactics.

Alexander married three times: Roxana, out of love; and Stateira II and Parysatis II for political reasons. In addition, he had a long and close (and generally assumed romantic) relationship with his friend, general, and bodyguard Hephaestion, the son of a Macedonian noble. Many historians of Alexander, both ancient and modern, noted Alexander's close relationship with Hephaestion. For example, the famed Greek philosopher Plutarch wrote that “in general, [Alexander] showed most affection for Hephaestion,” which was made clear when the only colleague allowed to read the letters sent to him from Alexander's mother, Olympias, was indeed Hephaestion. The trust built between the two men was undeniable; as modern Alexander the Great historian Robin Lane Fox wrote, “Hephaestion was the one whom Alexander loved, and for the rest of their lives their relationship remained as intimate as it is now irrecoverable: Alexander was only defeated once, the Cynic philosophers said long after his death, and that was by Hephaestion's thighs.” 

While there is no existing explicit description of a physical, romantic relationship between the two men, the existence of bisexual behavior in the ancient Greek world is well enough known, and the circumstantial evidence is compelling. What is absolutely certain is that Alexander loved Hephaestion, especially after the latter died suddenly of an unnamed fever in October of 324 B.C.E., and the king was overcome with grief. As Plutarch writes, “Alexander's grief was uncontrollable."

As a sign of mourning, he gave orders that the manes and tails of all horses should be shorn, demolished the battlements of all the neighboring cities, crucified the unlucky physician, and forbade the playing of flutes or any other kind of music for a long time, until finally, an oracle came from Ammon, commanding him to honor Hephaestion and sacrifice to him as a hero.” In addition to this grief, Alexander spent a reported fortune (over 200 million dollars in 21st-century money) on Hephaestion's tomb and was reportedly despondent for days. The stress from this may even have contributed to Alexander's failing health and detached mental state during his final months.

As was expected of all royal men of the period, Alexander married women who bore him children (including Alexander IV, born to Roxana). However, his love for men was likely just as strong as his love for women, as his deeply felt relationship with Hephaestion shows.