Wei Shen's childhood friend and sometime errand boy for the Water Street Gang, Jackie Ma likes to big himself up, but no one takes him that seriously. In Sleeping Dogs their paths keep crossing and re-crossing.
Inspector Jane Teng is a career officer in the HKPD. She is pursuing a vendetta against the Triads and works with Wei Shen on four separate cases including murders in the street racing scene and a serial killer on the loose in Hong Kong.
Pendrew is a senior officer in the HKPD, and Jane Teng's and Wei Shen's boss. He has a long-standing and close relationship with Uncle Po, the chairman of the Sun On Yee. Pendrew is driven by an "ends justify the means" attitude and is not afraid to bend the rules and violate procedures to get results.
David Wa-Lin "Uncle" Po
Uncle Po is the Dragon Head of the Sun On Yee Triad. A cautious man with a benign grandfatherly demeanour, Uncle Po is perfectly happy to murder in order to get his way. Wei's ambition is to take him down.
Sam “Dogeyes” Lin
Dogeyes grew up poor but naturally cool, and used his charm to earn membership in the Sun On Yee where he is a Red Pole. A borderline psychopath and full-time pimp, one of his victims was Mimi Shen, whom he seduced and turned into a prostitute and who later committed suicide. Mimi was Wei’s sister.
Before he left Hong Kong, Wei Shen was a student at Sifu Kwok’s martial arts school. When Shen returns to continue his training, Kwok asks him to track down eleven precious Chinese Zodiac Statues, stolen from him by a former pupil. Kwok promises to teach Shen a new move for each statue he recovers.
Sandra comes from a wealthy family, her life is equal parts privilege and danger. She has just two passions: fast cars and dangerous men, and attracted to Wei’s gangster cool she introduces him to Hong Kong’s illegal street racing scene.
Winston grew up in a housing project with other members of the Sun On Yee Triad, including his close friend Dogeyes Lin. He joined the Triads at a young age, working his way up to become Red Pole of Water Street Gang. However, due to his poor leadership, Water Street Gang has become the weakest faction in the Sun On Yee and is a target for takeover by the other gangs. Winston also happens to be Jackie Ma’s boss, providing Wei Shen with an ideal opportunity to infiltrate the Triads.