| Hugh Bonneville | Robert Crawley, Earl of Grantham |
| Laura Carmichael | Lady Edith Crawley |
| Jim Carter | Charles Carson |
| Raquel Cassidy | Baxter |
| Brendan Coyle | John Bates |
| Tom Cullen | Anthony Gillingham |
| Michelle Dockery | Lady Mary Crawley |
| Kevin Doyle | Joseph Molesley |
| Joanne Froggatt | Anna Bates |
| Lily James | Lady Rose MacClare |
| Robert James-Collier | Thomas Barrow |
| Allen Leech | Tom Branson |
| Phyllis Logan | Mrs. Hughes |
| Elizabeth McGovern | Cora Crawley, Countess of Grantham |
| Sophie McShera | Daisy Mason |
| Lesley Nicol | Mrs. Patmore |
| David Robb | Dr. Clarkson |
| Maggie Smith | Violet Crawley, Dowager Countess of Grantham |
| Penelope Wilton | Isobel Crawley |
| Sue Johnston | Miss Denker |
| Rade Serbedzija | Prince Kuragin
(as Rade Sherbedgia) |
| Louis Hilyer | Inspector Vyner |
| Howard Ward | Sergeant Willis |
| Dean Ashton | Evans |
| Jeremy Swift | Spratt |
| Michael Fox | Andy |
| Peter Egan | Hugh 'Shrimpie' MacClare, Marquess of Flintshire |
| Phoebe Nicholls | Susan MacClare, Marchioness of Flintshire |
| Penny Downie | Lady Sinderby |
| James Faulkner | Lord Sinderby |
| Matt Barber | Atticus Aldridge |
| Sophie Cosson | Prostitute |
| James Phelips | Waiter |
| Catherine Steadman | Mabel Lane Fox |
| Sarah Crowden | Lady Manville |
| Darren Machin | Basil Shute |
| Paul Copley | Mr. Mason |
| James Francis Andrews | Wedding Guest
(uncredited) |
| Oliver Barker | George Crawley
(uncredited) |
| Zac Barker | George Crawley
(uncredited) |
| Ray Burnet | The Verger
(uncredited) |
| Ethan Chapples | Atticus' Brother
(uncredited) |
| Alexander Cooper | Rules Waiter
(uncredited) |
| Roman Green | Veteran
(uncredited) |
| Fifi Hart | Sybbie Branson
(uncredited) |
| Jefferson King | Detective
(uncredited) |
| Maya Lindh | Lady Annabelle MacClare
(uncredited) |
| Hugh O'Brien | Policeman
(uncredited) |
| Tina Simmons | The Velvet Violin Club Guest
(uncredited) |
| Albert Tang | Club Guest
(uncredited) |
| Nathan Webb | Lieutenant NRV
(uncredited) |