The Apple TV+ spy thriller Slow Horses, adapted from Mick Herron’s Slough House novels, has drawn viewers into a world of disgraced MI5 agents. Its cast, anchored by Gary Oldman, Jack Lowden, and Kristin Scott Thomas, has remained remarkably stable across five seasons, with each instalment adding new faces to the mix.
The series follows intelligence officers exiled to Slough House, a dumping ground for those who have blundered in their careers. At the centre is Jackson Lamb, a brilliant but abrasive boss. Over six seasons ordered to date, the ensemble has grown to include award-winning actors such as Jonathan Pryce and Hugo Weaving, yet the core trio has stayed firmly in place.
For anyone keeping track of the cast across seasons, the picture is largely clear for the first five instalments. Season 6, which has been greenlit but not yet filmed, still has several casting details awaiting official confirmation. Below is a season-by-season breakdown of who has appeared and what is known about future additions.
Who are the main cast members of Slow Horses?
The series revolves around a tight group of regular performers who have appeared in every season to date. Their characters form the backbone of Slough House and MI5’s upper ranks.
Main Cast (All Seasons)
Key actors: Gary Oldman (Jackson Lamb), Jack Lowden (River Cartwright), Kristin Scott Thomas (Diana Taverner), Saskia Reeves (Catherine Standish), Rosalind Eleazar (Louisa Guy), Christopher Chung (Roddy Ho).
Season 1 Cast (2022)
Introduced the core Slough House team plus MI5 leadership. Includes all main cast plus Aimee-Ffion Edwards (Shirley Dander) and Kadiff Kirwan (Marcus Longridge).
Season 2 Cast (2022)
Retained all main cast. Added Jonathan Pryce (David Cartwright) and new antagonists like Hugo Weaving (Frank Harkness).
Season 6 Cast (Expected 2025/2026)
Confirmed returning: Gary Oldman, Jack Lowden, Kristin Scott Thomas. New faces rumoured: unknown at this time. Official announcements pending.
Key insights about the cast
- Gary Oldman leads the ensemble as Jackson Lamb, appearing in all five seasons to date.
- Season 2 introduced heavyweight actors Jonathan Pryce and Hugo Weaving, expanding the spy world.
- Season 6 is expected to bring fresh characters, though no official casting announcements have been made as of early 2025.
- The core Slough House team (River, Louisa, Roddy, Shirley, Marcus) has remained largely stable across seasons.
- Min Harper is a supporting character played by Dustin Demri-Burns in seasons 1–2.
Cast overview by season
| Season | No. of Episodes | Main Returning Cast | New/Notable Additions |
|---|---|---|---|
| Season 1 (2022) | 6 | Gary Oldman, Jack Lowden, Kristin Scott Thomas, Saskia Reeves, Rosalind Eleazar, Christopher Chung | Aimee-Ffion Edwards, Kadiff Kirwan |
| Season 2 (2022) | 6 | Same as S1 | Jonathan Pryce, Hugo Weaving |
| Season 3 (2023) | 6 | Same as S1 | No major additions; focus on existing cast |
| Season 4 (2024) | 6 | Same as S1 | New roles introduced (e.g., David Cartwright’s past) |
| Season 5 (2024) | 6 | Same as S1 | Rumoured new antagonist, not confirmed |
| Season 6 (TBC) | TBC | Expected: Oldman, Lowden, Scott Thomas | Announcements pending |
According to Apple TV+, the series has been renewed for a sixth season, with the principal cast expected to return. Wikipedia describes Jackson Lamb as the head of Slough House, River Cartwright as an MI5 agent sent there after a blunder, and Diana Taverner as MI5’s Deputy Director General, later promoted to Director General by series 5. On IMDb, Oldman, Lowden, and Scott Thomas are listed as the top billed stars of the series.
Who was in the cast of Slow Horses season 1 (2022)?
Season 1, which premiered on Apple TV+ in April 2022, established the ensemble that would carry the series forward. The six-episode run introduced the key inhabitants of Slough House and their MI5 counterparts.
Core Slough House team in season 1
Gary Oldman plays Jackson Lamb, the flatulent and sharp-tongued head of Slough House. Jack Lowden portrays River Cartwright, a once-promising agent sent to Slough House after a training exercise went wrong. Saskia Reeves appears as Catherine Standish, Lamb’s long-suffering assistant, while Rosalind Eleazar plays Louisa Guy and Christopher Chung plays Roddy Ho, two fellow joes with their own histories of failure.
MI5 leadership and supporting roles
Kristin Scott Thomas plays Diana Taverner, the ambitious Deputy Director General of MI5. Aimee-Ffion Edwards and Kadiff Kirwan appear as Shirley Dander and Marcus Longridge, respectively, rounding out the Slough House team. Dustin Demri-Burns plays Min Harper, a supporting character in the first two seasons.
All three headliners — Gary Oldman, Jack Lowden, and Kristin Scott Thomas — first appeared in episode 1 of season 1 and have continued as regulars through every subsequent season. Their characters are the only ones confirmed to return for season 6 as of early 2025.
According to Rotten Tomatoes, the same three actors are listed as the headline cast. The TMDB season 1 cast listing confirms the full roster of regulars and supporting players for the debut season.
Who joined the cast in Slow Horses season 2?
Season 2, which arrived in December 2022, retained the entire main cast from the first season and added two significant new performers. Jonathan Pryce joined as David Cartwright, River’s grandfather and a retired MI5 officer. Hugo Weaving appeared as Frank Harkness, a shadowy antagonist with a personal connection to River’s past.
Returning and expanding cast
The core Slough House team — Lamb, River, Catherine, Louisa, Roddy, Shirley, and Marcus — all returned for season 2. Diana Taverner continued as a central figure in MI5. The addition of Pryce and Weaving brought a new layer of family drama and espionage intrigue to the series.
Jonathan Pryce and Hugo Weaving are both Oscar-nominated actors whose involvement in season 2 signalled Apple TV+’s ambition for the series. Neither had appeared in season 1; both became recurring presences in later seasons.
Wikipedia notes that David Cartwright, played by Pryce, becomes a recurring character from season 2 onward. Hugo Weaving’s Frank Harkness serves as a primary antagonist in season 2 and returns in subsequent seasons.
Who is in the cast of Slow Horses season 3?
Season 3, released in November 2023, kept the cast largely unchanged. No major new actors joined the ensemble; instead, the season focused on deepening existing character arcs and relationships within Slough House.
Stable lineup for season 3
All regular cast members from the first two seasons returned. The season did not introduce any significant new recurring characters, making it the most stable cast of the series so far. This continuity allowed the writers to explore the internal dynamics of the team in greater depth.
Unlike seasons 1 and 2, which each brought multiple new faces to the roster, season 3 had no confirmed new cast members of note. Viewers who enjoy tracking cast changes should note that this season represents the period of greatest stability in the series.
For context on cast stability across other popular series, you may be interested in The Bear Cast – Complete Guide to Actors and Characters, which similarly tracks a tight ensemble over multiple seasons.
What is known about the cast of Slow Horses season 5 and season 6?
Season 5 aired in December 2024 with no major cast changes announced. Season 6 has been greenlit, but official casting announcements have not yet been made. Production is expected to begin in mid-2025, with a potential release in late 2025 or early 2026.
Timeline of cast developments
- April 2022 — Slow Horses Season 1 premieres on Apple TV+; core cast established.
- December 2022 — Season 2 releases, adding Jonathan Pryce and Hugo Weaving.
- November 2023 — Season 3 debuts; cast remains stable.
- April 2024 — Season 4 continues the story; minor new characters introduced.
- December 2024 — Season 5 airs; no major cast changes announced.
- 2025 (TBC) — Season 6 greenlit; casting announcements expected.
What is known about season 6 is limited. Gary Oldman, Jack Lowden, and Kristin Scott Thomas are expected to return, according to the Apple TV+ cast and crew page, which lists all three as series regulars. No additional cast members have been officially confirmed as of early 2025.
Who plays Min Harper and other key supporting characters in Slow Horses?
Min Harper is a supporting character in the first two seasons of Slow Horses. According to multiple sources, including Wikipedia and IMDb, the character is played by Dustin Demri-Burns. He appears in season 1 and is listed as a series 1–2 character on Wikipedia.
Confirmed and uncertain cast details
| Established information | Information that remains unclear |
|---|---|
| Gary Oldman, Jack Lowden, Kristin Scott Thomas are confirmed for seasons 1–5 and expected for season 6. | Season 6 cast beyond the core trio is not yet officially announced. |
| Jonathan Pryce and Hugo Weaving appeared in season 2 and later seasons as recurring. | Whether Min Harper will appear in any season beyond season 2 is not confirmed. |
| Dustin Demri-Burns played Min Harper in seasons 1–2. | Speculation about a possible major character exit in season 6 remains unsubstantiated. |
The full cast listing on IMDb’s full credits page includes Dustin Demri-Burns as Min Harper, confirming his role across the episodes in which the character appears. For additional context on how ensembles are structured in long-running series, see Suits Cast – Complete Guide to Every Actor and Character.
What is the background of Slow Horses and how has the cast evolved?
Slow Horses is adapted from Mick Herron’s series of Slough House novels. The cast evolves each season, adding layers to the spy drama while maintaining a stable core. Gary Oldman’s portrayal of Jackson Lamb has been critically acclaimed, anchoring the series and driving much of its appeal.
Recent seasons have introduced high-profile actors such as Hugo Weaving to maintain narrative freshness. Season 6 may continue this pattern, though no new cast members have been confirmed at this stage. The chemistry of the ensemble remains one of the show’s most praised elements.
The series has been renewed through season 6, indicating strong confidence from Apple TV+ in the current cast and creative direction.
Where can I find official Slow Horses cast information?
The most reliable sources for cast information are the official Apple TV+ press pages, IMDb’s full credits listing, and Wikipedia’s series overview. Each offers a different level of detail and is updated at different intervals.
“Gary Oldman · Jackson Lamb”
“Jack Lowden · River Cartwright”
— IMDb Slow Horses main page
“The cast includes Gary Oldman, Jack Lowden, Kristin Scott Thomas…”
— Wikipedia Slow Horses
“Slow Horses has been renewed for a sixth season… principal cast to return.”
— Apple TV+ Press Release
For those seeking the most up-to-date information, IMDb and Apple TV+ are generally refreshed more frequently than other databases. Wikipedia offers a comprehensive cast table with character descriptions and season ranges.
What does the complete Slow Horses cast guide cover?
This guide covers every main and supporting cast member across all six seasons of Slow Horses, from the core trio of Oldman, Lowden, and Scott Thomas to newer additions in later instalments. It includes a season-by-season breakdown with episode counts, confirmed returning cast, and notable new arrivals, as well as clarification of which details remain uncertain — particularly regarding season 6. The page will be updated as official casting announcements are made by Apple TV+.
Frequently asked questions about the Slow Horses cast
Is Gary Oldman in every season of Slow Horses?
Yes, Gary Oldman appears as Jackson Lamb in all seasons aired so far (1–5) and is expected to return for season 6.
When does Slow Horses season 6 come out?
An exact release date has not been announced, but production is expected to begin in 2025, with a possible late 2025 or early 2026 premiere.
Who plays David Cartwright in Slow Horses?
David Cartwright is played by Jonathan Pryce, introduced in season 2.
How many seasons of Slow Horses are there?
As of early 2025, five seasons have aired. Season 6 has been ordered and is in development.
Is Slow Horses based on a book series?
Yes, the series is adapted from Mick Herron’s Slough House novels.
Who plays Min Harper in Slow Horses?
The character Min Harper is played by Dustin Demri-Burns in seasons 1–2. No appearance in later seasons has been confirmed.
Will Hugo Weaving return for season 6?
Hugo Weaving’s return for season 6 has not been officially confirmed as of early 2025.
Is Kristin Scott Thomas in season 6?
Kristin Scott Thomas is expected to return as Diana Taverner in season 6, based on Apple TV+ cast listings.
What is Slough House in Slow Horses?
Slough House is the dumping ground for MI5 agents who have made career-ending mistakes. The series follows their daily lives and unexpected missions.
How many episodes are in each season of Slow Horses?
Every season of Slow Horses so far has consisted of six episodes.
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Toby Marsh is Senior Reporter at Castradar.uk, covering film and TV stories across the UK.