This thesis is to study performance techniques of Wilar, a leading character in Lakon Nok named Chaiyachet including its hislory, performance elements, dance patterns, technique and style. Research methodology are documentary, intervicwing experts, observing real performance and VCD, and researcher’s training with the experts. The research finds that Wilar is a cat who can think and act as a human being. She is the maid in service of Queen Suwincha. Her outstanding role appears in 3 episodes: Trickery of the Seven Concubines, Finding the Prince, and Mocking the King. Chaiyachet has been performed since Ayutthaya period. Its story is about King Chaiyachet is lured by his seven concubines to believe that Suwincha, his Queen, gives birth as a piece of wood. The Queen with Wilar is sent into exile. The King, after knowing the truth, goes out to search for his Queen. On his way, he is challenged by Naraithibet who is actually his son. He takes him to meet the Queen. While the King is waiting at the city gate, Wilar comes out and mocks him. Finally, the King and Queen meet with happiness. Wilar’s danc is characterized by the nature of the cat such as swift movements, facial expressions strongly knee flexing, leaning forword most of the time, jumpsing, and producing some cat sounds. Dancer who portrays Wilar’s role must understand the nature of movements and emotions of the cat in order to play this role perfectly. Researches on dance techniques for these special roles are rare. There should be more studies in order to enrich the dance knowledge.