Thimbron or Thibron (Greek: Θίμβρων; fl. 400–391 BC) was a Lacedaemonian general. He was sent out as harmost in 400 BC, with an army of about 5,000 men, to aid the Ionians against Tissaphernes, who wished to bring them into subjection. Thibron raised a substantial force of Peloponnesian troops and levies from other cities around Greece, but was initially unable to face the Persian army in the field. After he was joined by elements of the Ten Thousand, he challenged and defeated the Persian army on several occasions; seizing several cities before settling in to besiege Larissa. That siege proved fruitless, and Thibron was ordered to abandon it, and then replaced by another general, Dercylidas, before he could launch his next campaign. Upon his return to Sparta Thibron was tried and exiled for allowing his troops to plunder Sparta's allies in the region. In 391 BC, during the Corinthian War, Thibron was again dispatched to Ionia with an army, and was ordered to take aggressive action against the Persian satrap Struthas, who was pursuing a pro-Athenian, anti-Spartan policy. Thibron launched a number of successful raids into Persian territory. His raids tended to be poorly organized, however, and Struthas took advantage of this to ambush one of Thibron's raiding parties. The Spartans were routed, and a large number of them, including Thibron, were killed.
It is likely that this Thibron is the same one mentioned by Aristotle as writing a treatise on the Spartan Constitution (Aristotle's Politics 7.1333b12; Jacoby, FGrHist 581; Tigerstedt, Legend of Sparta 1.110).