| Name | Character | Episodes |
|---|---|---|
| Bill Paterson | Dr. Douglas Monaghan | 20 |
| Dawn Steele | Justine McManus | 12 |
| Iain Robertson | Craig Stevenson | 12 |
| Archie Panjabi | Megan Sharma | 6 |
| Peter McDonald | Dr. Andrew Gemmill | 6 |
| Hugh Ross | Dean Claremont | 6 |
| Peter Guinness | Dr. Phillip Duncan | 3 |
| Douglas Henshall | Robert Dunbar | 2 |
| John Hannah | John Wade | 2 |
| Ben Miles | Ian O'Rourke | 2 |
| Barbara Flynn | Lt Col Petra Summers | 2 |
| James Fleet | Findlay Morrison | 2 |
| Colin Salmon | Peter Locke | 2 |
| Peter Capaldi | Gordon Fleming | 2 |
| Neve McIntosh | Karen O'Rourke | 2 |
| Tanya Moodie | Alisha | 2 |
| Christina Cole | Rebecca Muir | 2 |
| Christine Bottomley | Mary Dunbar | 2 |
| Lesley Vickerage | Carol Morrison | 2 |
| Siobhan Redmond | Carol Fleming / Helen Reid | 2 |
| Michelle Collins | Katie Quinn | 2 |
| Rakie Ayola | Yemi | 2 |
| Michael Obiora | Lucas | 2 |
| Danny Midwinter | Daniel Blakemore | 2 |
| Phyllis Logan | Elaine | 1 |
| Ken Drury | Ron Goodall | 1 |
| Jeff Rawle | James Norman | 1 |
| Ron Donachie | Minister | 1 |
| Paul McGann | Christopher Chambers | 1 |
| Ronald Pickup | Alex Galt | 1 |
| Sheila Reid | Aggie the Chambermaid | 1 |
| Frances Grey | Caroline Jenson | 1 |
| Phoebe Thomas | Chloe | 1 |
| Stephen Lord | Angus Jenson | 1 |
| Shauna Macdonald | Rosie Galt | 1 |
| Lucy Griffiths | Rebecca | 1 |
| Tim Plester | Video Shop Assistant | 1 |
| Clare Grogan | Cathy | 1 |
| William Ruane | David | 1 |