William Tung Biu was a Hong Kong actor and horse racing commentator. Tung started off as a jockey with his family racing horse stable. He was then recruited to become a horse racing commentator. Due to his fame, he was invited to act in many movies beginning in the late 1970s. He appeared in several films with Jackie Chan during the 1980s and 1990s, such as playing Inspector "Uncle" Bill Wong in the original Police Story series, including his final movie role in Police Story 4: First Strike in 1996. Tung retired from horse racing commentating in 2000. Tung died in 2006 of lung failure.

Police Story is a Hong Kong action film series created by and starring Jackie Chan. It comprises seven films, variously directed by Jackie Chan, Stanley Tong, Benny Chan, and Ding Sheng, and produced by Raymond Chow, Leonard Ho, Jackie Chan, Barbie Tung, Willie Chan, Solon So and Yang Du. The first film Police Story was released on 14 December 1985. The film's success led to three sequels, one spin-off, and two reboots.