The main cast of the TV series "Slow Horses" includes:
- Gary Oldman as Jackson Lamb, the head of Slough House
- Jack Lowden as River Cartwright, an MI5 agent reassigned to Slough House
- Kristin Scott Thomas as Diana Taverner, Deputy Director General of MI5, "Second Desk"
- Rosalind Eleazar as Louisa Guy, a member of Slough House
- Christopher Chung as Roddy Ho, a tech expert at Slough House
- Saskia Reeves as Catherine Standish, office administrator at Slough House
- Aimee-Ffion Edwards as Shirley Dander, a Slough House operative with a troubled past
- Tom Brooke as JK Coe, a newer member at Slough House
- James Callis as Claude Whelan, a character in the series
- Ruth Bradley as Emma Flyte, Head of Security at MI5 and leader of the Dogs
- Jonathan Pryce as David Cartwright, River's grandfather and retired senior MI5 officer
- Nick Mohammed as Zafar Jaffrey, Mayor of London in the series
Season 5 features some new additions like Nick Mohammed and Hiba Bennani, and also continuing roles for recurring characters from earlier seasons.
