Antiochus III the Great

Antiochus took the Seleucid throne at eighteen in 223 BC, inheriting chaos after his brother's death. Early campaigns against Ptolemaic Egypt failed, but he spent the next decade clawing back control over central Asia Minor, Parthia, and Bactria, pushing as far as the Kabul valley and renewing ties with the Indian king Sophagasenus - exploits that earned him the epithet "the Great" and the old Persian title Basileus Megas. Returning west, he seized Coele-Syria, Phoenicia, and Judea from the Ptolemies. Then he turned toward the Greek city-states, antagonized Rome, and in 192 BC launched a war on the mainland with Hannibal as his advisor and the Aetolian League as his ally. He was crushed at Thermopylae in 191 BC and Magnesia in 190 BC, surrendering much of Asia Minor to Rome's allies. Rebellions reignited across what remained, and he died in 187 BC on another eastern expedition.