As a collection of history's worst tyrants and criminal masterminds gather to plot a war to wipe out millions, one man must race against time to stop them.
| Orlando Oxford | Ralph Fiennes |
| Polly | Gemma Arterton |
| Grigori Rasputin | Rhys Ifans |
| Morton | Matthew Goode |
| King George / Kaiser Wilhelm / Tsar Nicholas | Tom Hollander |
| Conrad Oxford | Harris Dickinson |
| Erik Jan Hanussen | Daniel Brühl |
| Shola | Djimon Hounsou |
| Kitchener | Charles Dance |
| Camp Guard #1 | Shaun McKee |
| Camp Guard #2 | Peter York |
| Emily Oxford | Alexandra Maria Lara |
| Young Conrad | Alexander Shaw |
| Boer Sniper | Bevan Viljoen |
| Kingsman Tailor #1 | Shaun Scott |
| Kingsman Tailor #2 | Andrew Bridgmont |
| Huge Machinery Shack Guard | Olivier Richters |
| Mata Hari | Valerie Pachner |
| Gavrilo Princip | Joel Basman |
| Dupont | Todd Boyce |
| Shepherd's Flock Member #2 | Richard Stephenson Winter |
| Shepherd's Flock Member #3 | Takako Akashi |
| Shepherd's Flock Member #4 | Thorston Manderlay |
| Shepherd's Flock Member #5 | Terence Anderson |
| Shepherd's Flock Member #6 | Andy Cheung |
| Archduke Franz Ferdinand of Austria | Ron Cook |
| Sophie, Duchess of Hohenberg | Barbara Drennan |
| Pretty Girl | Maja Simonsen |
| Saravejo General | Benedick Blythe |
| Young King George | Max Count |
| Young Kaiser Wilhelm | Emil Oksanen |
| Young Tsar Nicholas | George Gooderham |
| Queen Victoria | Alexa Povah |
| Tsarina Alix | Branka Katić |
| Tsarevich Alexei | Alexander Shefler |
| Grand Duchess Anastasia | Rosie Goddard |
| Grand Duchess Maria | Dora Davis |
| Grand Duchess Olga | Lucia Jade Barker |
| Grand Duchess Tatiana | Molly McGeachin |
| British Soldier | Angus Castle-Doughty |
| British Soldier #2 | Jed O'Hagan |
| British Soldier #3 | Thomas Mahy |
| British Soldier #4 | Connor Calland |
| Lieutenant | James Musgrave |
| Sarajevo Prison Warden | Martin Razpopov |
| Felix Yusupov | Aaron Vodovoz |
| Russian Maid | Gabriela Całun |
| Russian Master of Ceremonies | Gabriel Constantin |
| Russian Prostitute #1 | Vår Haugholt |
| Russian Prostitute #2 | Ronja Haugholt |
| Yusupov Guest #1 | Alyona Kazarova |
| Yusupov Guest #2 | Fiz Marcus |
| Yusupov Guest #3 | Nina Novich |
| Yusupov Guest #4 | Andrey Andreev |
| Vladimir Lenin | August Diehl |
| Arthur Zimmermann | Nigel Lister |
| German Foreign Office Worker #1 | Daniel Vernan |
| German Foreign Office Worker #2 | Nigel Pilkington |
| Admiralty Military Intel Officer | Ed Cooper Clarke |
| Young Codebreaker | Stevee Davies |
| Rita | Alison Steadman |
| Sandhurst PT | Russell Balogh |
| General Ludendorff | Kristian Nekrasov |
| Ludendorff Butler | Stefan Schiffer |
| Sandhurst Chaplain | Tim Bruce |
| Sandhurst Cadet | Hal Hillman |
| President Woodrow Wilson | Ian Kelly |
| Vice President | David Calvitto |
| General | Ian Porter |
| White House Butler | Simon Connolly |
| British Officer | Alexander Cobb |
| Archie Reid | Aaron Taylor-Johnson |
| Sergeant Major | Emun Elliott |
| Soldier | James Backway |
| British Spy | Cassidy Little |
| Captain Forrest | Neil Jackson |
| Black Watch Soldier #1 | Ben Ayers |
| Black Watch Soldier #2 | Gwithian Evans |
| Black Watch Soldier #3 | Cory Stuckey |
| Storm Trooper | Timon Staehler |
| German Soldier #1 | Timothy Blore |
| Corporal Johnstone | Ross Anderson |
| Sergeant Major Atkins | Robert Aramayo |
| Kings Liverpool Soldier #1 | Remus Brooks |
| Kings Liverpool Soldier #2 | Felix Mosse |
| Kings Liverpool Soldier #3 | Will Pattle |
| Pub Girl #1 | Amy Leeson |
| Pub Girl #2 | Dolores Carbonari |
| United States Ambassador | Stanley Tucci |
| United States Embassy Secretary | Pippa Winslow |
| Moustached Man | David Kross |
| Housekeeper (uncredited) | Katarina Martin |
| Maid (uncredited) | Kya Garwood |
| Mayor of Sarajevo (uncredited) | Constantine Gregory |
| Russian General (uncredited) | Hal Fowler |
| Russian Sheppard (uncredited) | Renars Latkovskis |
| Bath Boy (uncredited) | Jack Cunningham-Nuttall |
| Soldier (uncredited) | Chloé Booyens |
| Officer Cadet (uncredited) | Tiago Martins |
| Kings Liverpool Soldier | Ryan Noire |
