Nai Khanom Tom was a famous practitioner of Muay Thai. Around 1774, he was captured along with other Thai prisoners, either in a skirmish or at the fall of the ancient capital of Siam of Ayutthaya. He was brought to Rangoon in Burma, where the Burmese King Mangra was holding a religious festival in honor of Buddha's relics. The festivities included many forms of entertainment. King Mangra was reported to be curious to see how the various fighting styles of Burma and other countries would compare. At one point, he wanted to see how Muay Boran would compare to the Burmese art Lethwei. Nai Khanomtom was selected to fight against the Burmese champion. Nai Khanomtom did a Wai Kru pre-fight dance which puzzled all of the Burmese. When the fight began, he charged out and, using punches, kicks, elbows, and knees, quickly pummeled the Burmese.

The referee was reported to have stated that the Burmese opponent was distracted by the Wai Kru, so the knockout was invalid. The King then asked if Nai Khanomtom would fight nine other Burmese champions to prove himself. He agreed and fought them all, one after the other with no rest periods between fights. The last Burmese was reputed to be a great boxing teacher. Nai Khanomtom defeated them all in a superior fashion.

King Mangra was so impressed that he remarked, "Every part of the Thai is blessed with venom. Even with his bare hands, he can fell nine or ten opponents. As his lord master was incompetent, the country was lost to the enemy. If his lord had been any good, there was no way the City of Ayutthaya would ever have fallen."

He granted Nai Khanomtom freedom along with either riches or two beautiful Burmese wives. Nai Khanomtom chose the wives as he said that money was easier to find. He then departed with his wives for Siam. Other variations of this story had him also winning the release of his fellow Thai prisoners. His feat is celebrated every March 17 as "Boxer's Day" or "National Muay Thai Day" in his honor and that of Muay Thai's.

Today, some have wrongly attributed the legend of "Nai Khanomtom" to the King Naresuan, who was also once taken by the Burmese.

There is also the legend of Skeng Man Nang (c700). He was a mutant child born with three legs. This made his parents foresake him, but he was taken in by a monastery in the north of the country. Here he was taught muay boran by the monks, and it soon became apparent that his extra leg gave him considerable fighting prowess against bipedal foes. However, he committed suicide after becoming mentally unbalanced by the cries of "choi soi kap" ("three legged mutant" in ancient thai). His existence has only recently come to light, after the royal archives at Ayutthaya which were destroyed by Burmese invaders were recovered. (Reference: Professor Peter Shaw, School of Oriental and African Studies, London)