| Name | Character | Episodes |
|---|---|---|
| Clare Holman | Dr. Laura Hobson | 41 |
| Rebecca Front | Chief Superintendent Jean Innocent | 41 |
| Laurence Fox | Detective Sergeant James Hathaway | 41 |
| Kevin Whately | Detective Inspector Robert 'Robbie' Lewis | 41 |
| Alex MacQueen | Dr. Julius Fisher | 6 |
| Naomi Scott | Sahira Desai | 2 |
| Taron Egerton | Liam Jay | 2 |
| Edward Fox | Dr. Yardley | 2 |
| Ariyon Bakare | Carl Drew | 2 |
| Babou Ceesay | DC Alex Gray | 2 |
| Nicholas Jones | Philip Hathaway | 2 |
| Tuppence Middleton | Vicki Walmsley | 2 |
| Beatie Edney | Justine Skinner | 2 |
| Alison Steadman | Rev. Martha Seager | 2 |
| Sanjeev Bhaskar | Kanan Dutta | 2 |
| Emily Joyce | Jane Grace | 2 |
| Peter Davison | Peter Faulkner | 2 |
| Lucy Speed | Louise Cornish | 2 |
| Miranda Raison | Stella Drew | 2 |
| Andrew Paul | Ron Tibitt | 2 |
| Lia Williams | Emma Barnes | 2 |
| Lesley Vickerage | Katherine Dutta | 2 |
| Catherine Steadman | Polly Beatty | 2 |
| Doreen Mantle | Joan | 2 |
| Neil Stuke | Professor Andrew Crane | 2 |
| Tim Pigott-Smith | Jasper Hammond | 2 |
| Camilla Power | Tara Faulkner | 2 |
| Jason Durr | DI Peterson | 2 |
| Dominic Mafham | Frank McLean | 2 |
| Bobby Lockwood | Sam Langton | 2 |
| Stephen Churchett | Richard Seager | 2 |
| Josh Bolt | Adam Tibitt | 2 |
| Rosie Cavaliero | 2 | |
| Tom Brooke | Brian Miller | 2 |
| Joanna Lumley | Esme Ford | 1 |
| Jonathan Bailey | Titus Mortmaigne | 1 |
| Adrian Rawlins | Harry Bundrick | 1 |
| Josh O'Connor | Charlie Stephenson | 1 |
| Saskia Reeves | Alison McLennan | 1 |
| Juliet Aubrey | Selina Mortmaigne | 1 |
| Lucy Boynton | Zoe Suskin | 1 |
| Matilda Ziegler | Helena Wright | 1 |
| Bradley James | Jack Roth | 1 |
| Nicholas Farrell | Charles Milner | 1 |
| Finn Cole | Ollie Tedman | 1 |
| Paul Reynolds | Mr. Davies | 1 |
| Annabelle Apsion | Babs Temple | 1 |
| Oliver Milburn | Charlie Newton | 1 |
| Roxanne McKee | Briony Keagan | 1 |
| Harry Lloyd | 1 | |
| Emily Beecham | Nell Buckley | 1 |
| Ian McNeice | Reverend King | 1 |
| David Hayman | 1 | |
| Hattie Morahan | Ruth Brooks | 1 |
| Toby Stephens | David Connelly | 1 |
| James Fleet | Dr. Alex Falconer | 1 |
| Con O'Neill | Dr. Bob Massey | 1 |
| Cheryl Campbell | 1 | |
| Art Malik | 1 | |
| Perdita Weeks | 1 | |
| Sally Bretton | Eve Rigby | 1 |
| Katia Winter | 1 | |
| Alastair Mackenzie | Sebastian Anderson | 1 |
| Nina Sosanya | Lilian Hunter | 1 |
| Freddie Fox | Sebastian Dromgoole | 1 |
| Anna Massey | Prof. Margaret Gold | 1 |
| David Calder | Andrew Lipton | 1 |
| Susannah Doyle | Jean Croft | 1 |
| James Fox | 1 | |
| Celia Imrie | Michelle Marber | 1 |
| Ophelia Lovibond | Jessica Rattenbury | 1 |
| Juliet Stevenson | Diana Ellerby | 1 |
| Anna Chancellor | Judith Suskin | 1 |
| Anna Madeley | Anne Sadikov | 1 |
| Cherie Lunghi | Grace Orde | 1 |
| Rachael Stirling | Zoë Kenneth | 1 |
| Selina Cadell | 1 | |
| Aisling Bea | Hotel Receptionist | 1 |
| Tom Mison | Dorian Crane | 1 |
| Deborah Findlay | Lady Hugh | 1 |
| Julie Cox | Miranda Thornton | 1 |
| Robert Hardy | Sir Arnold Raeburn | 1 |
| Warren Clarke | Roger Temple | 1 |
| Lucy Cohu | Marion Hammond | 1 |
| Daniel Sharman | Richard Scott | 1 |
| Adam Levy | 1 | |
| Zoe Telford | Freya Carlisle | 1 |
| Gerard Horan | DC Hooper | 1 |
| Adam James | Ethan Croft | 1 |
| Emma Cleasby | Jessica Neill | 1 |
| Rita Davies | Edna O'Brien | 1 |
| Timothy West | Donald Terry | 1 |
| Richard Dillane | Theodore Platt | 1 |
| John Salthouse | 1 | |
| David Westhead | Leon Suskin | 1 |
| Daniel Lapaine | Kit Renton | 1 |
| Alan Davies | Marcus Richards | 1 |
| Helen Grace | Gwen Milner | 1 |
| Trevor Byfield | Bone | 1 |
| Josephine Tewson | Hazel O'Brien | 1 |
| Geoffrey Breton | Joe Myers | 1 |
| Nathaniel Parker | Philip Coleman | 1 |
| Ruth Gemmell | Robyn Strong | 1 |
| Nancy Carroll | Anne Rand | 1 |
| Alex Jennings | Rev. Conor Hawes | 1 |
| Jenny Seagrove | Cecile Rattenbury | 1 |
| Camilla Arfwedson | Scarlett Mortmaigne | 1 |
| Richard Johnson | Augustus Mortmaigne | 1 |
| Caroline O'Neill | Susan Chapman | 1 |
| Diana Quick | Gwen Raeburn | 1 |
| Katrine De Candole | Davina Garland | 1 |
| Cara Horgan | 1 | |
| David Ryall | Mr. Cooper | 1 |
| Anthony Higgins | 1 | |
| Jamie Michie | Brian Kaye | 1 |
| Bryan Dick | Phil Beaumont | 1 |
| Richard Lintern | Sefton Linn | 1 |
| Olly Alexander | 1 | |
| Patrick Baladi | Robert Fraser | 1 |
| Ronan Vibert | Simon Monkford | 1 |
| Lucy Griffiths | Madeleine Escher | 1 |
| Matthew Marsh | Henry McEwan | 1 |
| Richard Durden | John Gracey | 1 |
| Ciarán McMenamin | Nick Addams | 1 |
| Wendy Nottingham | 1 | |
| Abigail Hardingham | Jessica Lake | 1 |
| Stella Gonet | Frances Woodville | 1 |
| Guy Henry | Professor Pelham | 1 |
| Liz Crowther | Mrs. Leeming | 1 |
| Kate Miles | Nova Rose | 1 |
| Leanne Rowe | Carly Cliff | 1 |
| Zoe Boyle | Hope Ransome | 1 |
| Tom Riley | Philip Horton | 1 |
| Haydn Gwynne | Sandra Walters | 1 |
| Ben Aldridge | Daniel Rattenbury | 1 |
| Julian Wadham | Tom Rattenbury | 1 |
| Neil Pearson | Dr. Stringer | 1 |
| David Soul | Paul Yelland | 1 |
| Anna Wilson-Jones | Stanza Massey | 1 |
| Antonia Campbell-Hughes | Chloe Brooks | 1 |
| Annabel Mullion | Thea Falconer | 1 |
| Lorcan Cranitch | Liam Cullen | 1 |
| Andrew Knott | 1 | |
| Georgia Taylor | Honey Addams | 1 |
| Hugh O'Conor | Father Jasper | 1 |
| Sian Thomas | Ingrid Nielson | 1 |
| Maureen Beattie | 1 | |
| Andrew Hawley | Jez Haydock | 1 |
| Daniela Nardini | 1 | |
| Anna Koval | Diane Baxter | 1 |
| Jack Gordon | James Coupland | 1 |
| Michael Pennington | Dr. Melville | 1 |
| Marty Cruikshank | Woman Interviewee | 1 |
| Shola Adewusi | Cleaner | 1 |
| Christopher Bowen | Professor Andrew Crompton | 1 |
| Pippa Bennett-Warner | Nina Clemens | 1 |
| Tabitha Wady | Ava Taylor | 1 |
| Jo-Anne Stockham | Helen Mitchell | 1 |
| Junix Inocian | 1 | |
| Leila Mimmack | Yasmin Randall | 1 |
| Elize du Toit | Andrea De Ritter | 1 |
| Kemi-Bo Jacobs | WPC Julie Lockhart | 1 |
| Kemi-Bo Jacobs | DC Lockhart | 1 |
| Chiké Okonkwo | Jonjo Read | 1 |
| Eva Sayer | Anna Mallory | 1 |
| Kathryn O'Reilly | Poppy Toynton | 1 |
| Bruce Mackinnon | Conan Jones | 1 |
| Ian Mercer | Lester Garvey | 1 |
| Edwin Thomas | Reuben Beatty | 1 |
| Simon Wilson | Dr. Matt Whitby | 1 |
| Harriet Madeley | Emily Robinson | 1 |
| Stephanie Street | Lakshmi Eyre | 1 |
| Jaygann Ayeh | Nate | 1 |
| Kazia Pelka | Susan Banks | 1 |
| Tom Goodman-Hill | 1 | |
| Philip Battley | Will McEwan | 1 |
| Sophie Ward | Isobel Crompton | 1 |
| Michael Simkins | Manfred Canter | 1 |
| Natalie Dew | Sophie Barton | 1 |
| Hilton McRae | 1 |