Khon, the ancient Thai mask dance-drama, is one of the most well-known traditional theatre genres in the Indo-China Peninsula; it dates back to the early 16th century. Traditionally it was developed under the patronage of Thai kings and royal families from the Ayutthaya period to the early 20th century. With a strong martial style in its movements, khon was once performed by males only. Though female performers began to take female roles in khon plays starting from the early 20th century, male performers are still the main attraction. The most distinctive features of the genre are martial style movements of male performers (especially the ogre and monkey roles) and their colorful, refined masks. Each mask represents a particular character in Ramakien which is a Thai version of Indian epic Ramayana and the only story source of a khon play. Owing to its distinctive style of martial arts, khon is especially good for war and martial repertoires. Like most Asian traditional theatres, khon performance is accompanied by a traditional orchestra, the pipat ensemble, with chanters and chorus who chant, sing and speak for the actors. For this reason, khon is often referred to as pantomime. This paper aims to introduce khon’s origins and history, as well as its artistic features and changes in modern Thai society.