Slow Horses is a British spy thriller television series based on the Slough House series of novels by Mick Herron, created by Will Smith. It follows an MI5 unit where disgraced or failed agents are consigned, under the supervision of Jackson Lamb (Gary Oldman). It also stars Jack Lowden, Kristin Scott Thomas, Sophie Okonedo, Jonathan Pryce, Saskia Reeves, Rosalind Eleazar, Christopher Chung and Aimee-Ffion Edwards.

The series premiered on Apple TV+ on 1 April 2022 to highly positive reviews. The first four series have adapted the novels Slow Horses, Dead Lions, Real Tigers, Spook Street, respectively. The fifth series, based on the novel London Rules, premiered on 24 September 2025. Slow Horses has been renewed for a sixth and seventh series, based on the novels Joe Country and Slough House (series 6) and Bad Actors (series 7).

Slough House is a banishment room for MI5 service rejects who have seriously failed a task but not badly enough to get sacked. Those consigned there are known as "slow horses", a play on the name of the place itself, Slough House, and an expression for people who are slow at thinking and action. Those assigned there are expected to endure dull, routine tasks, along with occasional verbal abuse from their miserable boss, Jackson Lamb, who anticipates that they will leave out of boredom or frustration. Life in Slough House is defined by drudgery. Yet the Slow Horses somehow get involved in investigating cases that endanger Britain.

Notable other characters appearing in more than one series include:

Notable other characters appearing in Series 1 include:

Notable other characters appearing in Series 2 include:

Notable other characters appearing in Series 3 include:

Notable other characters appearing in Series 4 include: