| Name | Character | Episodes |
|---|---|---|
| Vicky McClure | Mrs. Jones | 24 |
| Brenock O'Connor | Tom Harris | 24 |
| Ronkẹ Adékoluẹjo | Jack Starbright | 24 |
| Otto Farrant | Alex Rider | 24 |
| Stephen Dillane | Alan Blunt | 23 |
| Marli Siu | Kyra | 18 |
| Ace Bhatti | Crawley | 15 |
| Nyasha Hatendi | Smithers | 15 |
| Macy Nyman | Steph | 9 |
| Sofia Helin | Julia Rothman | 8 |
| Jason Wong | Nile | 8 |
| Haluk Bilginer | Dr. Greif | 7 |
| Rakie Ayola | Jo Byrne | 7 |
| Daniel Francis-Swaby | Dan Williams | 7 |
| Ana Ularu | Eva Stellenbosch | 6 |
| Toby Stephens | Damian Cray | 6 |
| Charithra Chandran | Sabina Pleasance | 6 |
| Shelley Conn | Laura Kellner | 6 |
| Hari Dhillon | Ed Pleasance | 6 |
| George Sear | Parker Roscoe | 5 |
| Joseph Mydell | Johnny Matovu | 5 |
| Nathan Clarke | Arrash | 4 |
| Liam Garrigan | Martin Wilby | 4 |
| Jonathan Slinger | Charlie Roper | 4 |
| Katrin Vankova | Laura | 4 |
| Eline Powell | Syl | 3 |
| Kevin McNally | Max Grendel | 3 |
| Earl Cave | James | 3 |
| Simon Shepherd | Sir David Friend | 3 |
| Stuart Bowman | Sean Palmer | 3 |
| Howard Charles | Wolf | 3 |
| Andrew Buchan | Ian Rider | 2 |
| Tom Mothersdale | Smoking Mirror | 2 |
| Steven Brand | Michael Roscoe | 2 |
| Naomi Wirthner | Dr. Lambert | 2 |
| Simon Paisley Day | Dr. Baxter | 2 |
| Llewella Gideon | Miss Baker | 2 |
| Ben Peel | Fox | 2 |
| Philipp Christopher | Luka Kovacic | 2 |
| Ky Discala | Eagle | 2 |
| Josh Herdman | Stan | 1 |
| Donald Sage Mackay | General Lomis | 1 |
| Lucy Akhurst | Lady Caroline Friend | 1 |
| Alana Boden | Fiona Friend | 1 |
| Flaminia Cinque | Housekeeper at Friend Mansion | 1 |
| Cara Horgan | Polly Hunton | 1 |
| Grant Crookes | Lieutenant Colonel (uncredited) | 1 |
| Ralph Prosser | Rafe | 1 |
| Justin Salinger | Aaron Limehouse | 1 |
| Todd Boyce | Colonel Brixham | 1 |
| Rose Reynolds | PC Geri Crawford | 1 |
| Jacqueline Boatswain | Immigration Officer Powell | 1 |
| Aaron Cobham | Agent Stokes | 1 |
| James Alexander | Langham | 1 |
| James Alexander | Mr. Langham | 1 |
| Daniel Eghan | Hotel Doorman (uncredited) | 1 |
| Michelle Greenidge | Maisie | 1 |
| Rory Alexander | Eric | 1 |
| Nigel Allen | Department Operative | 1 |
| Sebastian Orozco | Jonas | 1 |