K9 Cop

Main Role

• 
  Linda Chung

  Ma Chi Ho

  Main Role
• 
  Bosco Wong

  Lai Yat Tsau

  Main Role
• 
  Raymond Wong

  Fai Chung Lim

  Main Role

Support Role

• 
  Tracy Chu

  Lai Suk Si / "Jil"

  Support Role
• 
  Oscar Leung

  Ma Chi Chung [Suk Fan's husband and Wai Kin's son]

  Support Role
• 
  Rebecca Chan

  Chung Wai Kin / Madam Chung / "Ken" [Chi Ho's foster mother]

  Support Role
• 
  Angel Chiang

  Lai Suk Fan / Saam Mui / "Fanny" [Chi Chung's wife]

  Support Role
• 
  Jerry Koo

  Lui Kam Dong | Lui Kam Bo [Kam Dong's twin brother]

  Support Role
• 
  Kayi Cheung

  Lai Suk Chu / Dai Mui [Yat Tsau's older sister]

  Support Role
• 
  Aurora Li

  Chun Bo

  Support Role
• 
  Cecilia Fong

  So Fu Gwai

  Support Role
• 
  Jess Sum

  Ho Yuen Gwan

  Support Role
• 
  Jimmy Au

  Yeung On / Yeung Me

  Support Role
• 
  LuLu Kai

  Chung San Gwong

  Support Role
• 
  Lau Kong

  Chung Ying May

  Support Role
• 
  Billy Luk

  Liu Lee Si / "Risk"

  Support Role
• 
  John Chan Support Role
• 
  Stephen Ho

  Lam Yuen Saam

  Support Role
• 
  Shally Tsang

  Lam Tai

  Support Role
• 
  Lee Hoi Sang Support Role
• 
  Forest Chan Support Role
• 
  Leo Tsang Support Role
• 
  Cheung Sze Yan Support Role
• 
  Chan Wing Chun Support Role
• 
  Ricky Wong Support Role
• 
  Dolby Kwan Support Role
• 
  Eddie Li Support Role
• 
  Henry Lo

  Seung Goon

  Support Role
• 
  Eric Chung

  Dai Chi Wai

  Support Role
• 
  Andy Sui Support Role
• 
  Janice Shum

  Law Shan / "Roseanne"

  Support Role
• 
  Samantha Chuk

  Charlie

  Support Role
• 
  Adam Ip Support Role
• 
  Chun Wong

  Dai Sum

  Support Role
• 
  Phoebe Chow

  Ying

  Support Role
• 
  Mark Ma

  Siu Bad Lim

  Support Role
• 
  Bob Cheung

  Au Yeung Siu Dig

  Support Role
• 
  Alex Yung

  Au Yeung Gin Wai

  Support Role
• 
  Gary Tam Support Role
• 
  Siu Lai Man Support Role
• 
  Ricky Lee Support Role
• 
  Doris Chow Support Role
• 
  Eddie Law Support Role
• 
  Kitterick Yiu Support Role
• 
  Ho Chun Hin Support Role
• 
  Athena Ng Support Role
• 
  Ng Pui Yu Support Role
• 
  Hebe Chan Support Role
• 
  Mina Kwok Support Role
• 
  Gloria Chan Support Role
• 
  David Do Support Role
• 
  Adrien Yau Support Role
• 
  Lucas Yiu Support Role
• 
  Judy Tsang Support Role
• 
  Yeung Shui Lun Support Role
• 
  Chan Min Leung Support Role
• 
  Chloe Nguyen Support Role
• 
  Eddie Ho Support Role
• 
  Hero Yuen Support Role
• 
  Dickson Wong Support Role
• 
  Terence Tung Support Role
• 
  Man Yeung Support Role
• 
  Glen Lee Support Role
• 
  Alan Tam Support Role
• 
  Kimmi Tsui Support Role
• 
  Milkson Fong Support Role
• 
  Jones Lee Support Role
• 
  Camy Ting Support Role

Guest Role

• 
  Kerry Chan

  Jackie (Ep. 1)

  Guest Role
• 
  Vicky Chan

  Vicky

  Guest Role
• 
  Kiko Leung

  Katie

  Guest Role
• 
  Jason Sze

  [Police officer]

  Guest Role
• 
  William Chu Guest Role
• 
  Cayley Mak

  [Pregnant woman] (Ep. 9)

  Guest Role
• 
  Louis Szeto Guest Role
• 
  Tse Ho Yat

  [Driver}

  Guest Role
• 
  Helen Seng Guest Role
• 
  Bobo Hoi Guest Role
• 
  Osanna Chiu

  [Dog handler]

  Guest Role

Bit part

• 
  Burmie Wong

  [Nurse] (Ep. 7, 15)

  Bit part
• 
  Danny Lo Bit part
• 
  Jonathan Lee Bit part
• 
  Miguel Choi Bit part
• 
  Calvin Chan Bit part

Unknown

• 
  Nicole Wong Unknown
• 
  Terrence Huang Unknown
• 
  Anthony Yu Unknown
• 
  Marco Lee Unknown
• 
  Andy Wong Unknown
• 
  Kinlas Chan Unknown