| Name | Character | Episodes |
|---|---|---|
| Stephen Graham | Mannix | 8 |
| Greta Scacchi | The Lady | 8 |
| Shira Haas | Iris Maplewood | 8 |
| Jacob Fortune-Lloyd | Charles Whiteman | 8 |
| Kyle Soller | Alfred Hillinghead | 8 |
| Amaka Okafor | Shahara Hasan | 8 |
| Synnøve Karlsen | Polly Hillinghead | 7 |
| Tom Mothersdale | Gabriel Defoe | 7 |
| Gabriel Howell | Elias | 7 |
| Michael Jibson | Barber | 6 |
| Nicholas Farrell | Chief Inspector Paxman | 5 |
| Amy Manson | Charlotte Hillinghead | 5 |
| Derek Riddell | Chief Inspector Calloway | 5 |
| Nitin Ganatra | Ishmael | 5 |
| Andrew Whipp | Ladbroke | 5 |
| Oscar Coleman | Jawad | 4 |
| Alexandra Roach | Maggie | 3 |
| Michael Byrne | Old Mullins | 3 |
| Will Merrick | Constable Byrne | 3 |
| Natalie Gavin | Sarah Mannix | 3 |
| Michael Shaeffer | Hayden Harker | 3 |
| Christopher Godwin | Reverend Kneale | 3 |
| Anna Calder-Marshall | Lady Harker | 2 |
| Mark Lewis Jones | Andrew Morley | 2 |
| David Horovitch | Rabbi Goldstein | 2 |
| Clare Perkins | Inspector Anderson | 2 |
| Selva Rasalingam | Prime Minister | 2 |
| Christopher Brand | Officer Webb | 2 |
| Edwin Thomas | Alby | 2 |
| Anna Calder-Marshall | Lady Agatha Harker | 1 |
| Kate Ashfield | Elaine Morley | 1 |
| Jordan Baker | June | 1 |
| Sheila Reid | Baroness Antonia Garner | 1 |
| Tom Mothersdale | The Body | 1 |
| Kurt Egyiawan | Philip Dust | 1 |
| Chaneil Kular | Syed Tahir | 1 |
| Jessamine-Bliss Bell | Marina | 1 |
| Nigel Hastings | Harker Bank Manager | 1 |
| Ellie James | Teri | 1 |
| Kae Alexander | Bothroyd | 1 |
| Jonny Coyne | Farrell | 1 |
| Tony Lucken | Boat Captain | 1 |
| Anthony O'Donnell | Clive Jones | 1 |
| Roderick Hill | Campsite Manager | 1 |
| Richard Tate | Professor Hamish McCabe | 1 |
| Jonathan Nyati | Vox Pop 1 | 1 |
| Ben Addis | Chandler | 1 |
| Natalie Dew | Aaliyah Tahir | 1 |