Main Cast:
* John Simm as Detective Inspector Sam Tyler
* Philip Glenister as Detective Inspector Gene Hunt
* Liz Carling as D.C. Annie Cartwright
* Dean Andrews as Detective Sergeant Ray Carling
* MyAnna Buring as D.C. WPC Gina "The Bird" Collier
* Marshall Lancaster as Detective Sergeant Chris Skelton
Recurring Characters:
* Barnaby Kay as D.C. "The Guv'nor" George "Ginger" Hobbs
* Jonathan Murphy as D.C. "The Punter" Peter "The Saint" Hayes
* Ian Bonar as Detective Superintendent Harry "The Boss" Henson
* Neil Bell as Superintendent "The Chief" James "Jimmy" Henson
* Sharon Small as Sam Tyler's wife, Sam (in flashbacks)
Guest Stars:
* David Bradley as Detective Inspector "Baxter" Baxter
* Frances Barber as Patricia "Patsy" Tyler
* Shaun Dooley as Brian "Bri" Smith
* Lee Ingleby as Derek "Der" Wynne
* Sarah Lancashire as Detective Inspector Laura "The Bird" Collier
* Craig Parkinson as D.C. "The Rover" Tony "The Boss" Smith
* Steven Mackintosh as D.C. "The Boss" Tony "The Rover" Smith
* Tom Goodman-Hill as John "Johnny" Tyler (Sam's father)
* Robert Pugh as D.C. "The Chief" James "Jimmy" Henson
This list includes the core cast and some of the most memorable recurring characters. There were many other guest actors who appeared in smaller roles.