Castle is the sixth studio album by Taiwanese singer Jolin Tsai. It was released on February 27, 2004, by Sony. Produced by Bing Wang, Peter Lee, Jay Chou, Jamie Hsueh, Huang Yi, and G-Power, it incorporated genres of pop, hip-hop, Latin, chanson, heavy metal, and Britpop. It was well received by music critics, who commented that it consolidated Tsai's successful development trend in the Chinese music scene.

Jolin Tsai is a Taiwanese singer, songwriter, and actress. Known as the "Queen of C-pop", she is one of the most influential pop cultural figures in the Chinese-speaking world. Recognized for her continual reinvention and versatility in musical style and visual image, she is regarded as a key figure in bringing dance-pop music into the mainstream in Greater China. She assumes creative control over all aspects of her career, and her works, which incorporate themes of societal issues and ideological connotations, have garnered both commercial success and critical acclaim.