The original film was by Hong Kong filmmaker Johnnie To (aka To Kei-Fung) in 2003, and remains to this day one of his best works. The five subsequent TV Movies used some of the same actors but as different characters.
01. PTU: Police Tactical Unit (2003) Dir. Johnnie To
The Tactical Unit TV Movies:
01. Tactical Unit: The Code (2008) Dir. Wing-cheong Law
02. Tactical Unit: No Way Out (2009) Dir. Lawrence Ah Mon
03. Tactical Unit: Human Nature (2009) Dir. Andy Ng
04. Tactical Unit: Comrades in Arms (2009) Dir. Wing-cheong Law
05. Tactical Unit: Partners (2009) Dir. Lawrence Ah Mon