Alexander the Great died in 323 BCE at just 32 years old—at the height of his power, with the known world under his control. But what killed him? That’s been a mystery for over two thousand years.

Ancient accounts say he developed a fever after days of drinking and died slowly over nearly two weeks. Some blamed malaria or typhoid. Others suspected poisoning—though the slow decline doesn’t quite fit. More recent theories suggest an autoimmune disorder, West Nile virus, or even Guillain-Barré syndrome.

His body, reportedly unchanged for days after death, only deepened the intrigue. Was it natural? Political? Something stranger?

What we know for sure: his death left a power vacuum that shattered his empire into warring kingdoms—and left historians with a trail of speculation that’s still unsolved.