One of the most common accounts of Alexander's death is that he was poisoned. This account is based on the writings of the ancient Greek historian Diodorus Siculus. Diodorus claims that Alexander was poisoned by his general Antipater, who was acting on the orders of the Macedonian regent Olympias.
Another account of Alexander's death is that he died from a fever. This account is based on the writings of the ancient Greek historian Quintus Curtius Rufus. Curtius claims that Alexander fell ill with a fever after bathing in the cold waters of the Euphrates River.
Finally, some historians believe that Alexander was killed by a combination of factors, including poisoning, fever, and exhaustion. They argue that Alexander's body was already weakened by several years of heavy campaigning, and that he was unable to withstand the effects of the fever and the poison.
Ultimately, the question of how Alexander the Great was killed remains a mystery. There is no definitive answer, and it is likely that we will never know for sure.