Simon Yam as Sergeant Wong Man-Chin / Dog Head

Tony Leung Ka-fai as Chan Chong-Shan / Hollow Man

Kate Tsui Tsz-Shan as Constable Ho Ka-Po / Piggy

Lam Suet as Ng Tung / Fatman

Maggie Shiu as Madam Fong

Eddie Cheung Siu-Fai as Chief Inspector Chan

Berg Ng Ting-Yip as Chan Chong-Shan's Gang Member

Wayne Lai Yiu-Cheung as Chan Chong-Shan's Gang Member

Samuel Pang King-Chi as Chan Chong-Shan's Gang Member

Susan Tse Suet-Sum as Master's Wife

Lau Kwok-Shing as Master

Wong Siu-Foon as IB Policeman

Au Hin-Wai as Senior Police Officer

Lo Chung-Him as Snakie

Frank Liu Zong-Ji as Chan Chong-Shan's Gang Member

Chan Kung as Chan Chong-Shan's Gang Member

Jimmy Wong as Officer Wo

Chiu Chi-Shing as Chan Chong-Shan's Gang Member

Hung Wai-Leung as Kidnapper

Pauline Yeung Yung-Lin as Cleaning Lady (uncredited)

Tam Kon-Chung as IB Policeman (uncredited)

Apple Chow Suk-Wai as Jewelry Store Clerk (uncredited)

Cheung Wing-Cheung as Loan Shark (uncredited)

Johnny Wong Yin-Ming as Man Eating in 7-Eleven (uncredited)

Sherwin Ming Tak-Fung as Sergeant Wong's Subordinate (uncredited)

Lee Long-Ming as Surveillance Unit Operator (uncredited)