We ranked the 15 best Slow Horses characters – and Jackson Lamb isn't No. 1

Slow Horses is back, reuniting fans with Jackson Lamb and his group of slightly shabby spies.

With the spy thriller now in its sixth season, we've produced a definitive ranking of Mick Herron's brilliant characters as they are presented in the TV series – not accounting for their presentation in the books.

Of course, this ranking isn't based on the characters' spy skills – that would be a very short list indeed. Instead, it's based on their entertainment value, the performances of the actors, how crucial they are to the show's success and their originality when compared with the wider media landscape.

Now, without further ado, read on for our full ranking of the 15 best characters in Slow Horses.

*Warning – contains spoilers for seasons 1-5 of Slow Horses*

15. Joanna Scanlan as Moira Tregorian

In many ways, Moira feels like she's stumbled into Slow Horses from another show. Perhaps this is because of actor Joanna Scanlan's background with former showrunner Will Smith, with the duo having starred in BBC comedy The Thick of It together. We sense Moira and Terri Coverley would get on, even if the former is significantly more efficient.

This mismatch between Moira and her surroundings at Slough House in season 4 make her a joy to watch and a comedy standout. It's bumped her above a number of other stellar supporting characters to appear on this list, despite her limited screen time thus far (she is set to return in season 6).

Her final moments in season 4, in which she pressured Claude Whelan into giving her back her job at the Park, also showed her to be a force to be reckoned with.

However, she is perhaps too straight-laced, lacking in both screen time and edge, to make it into the top tier of this and beyond number 15.

14. Kadiff Kirwan as Marcus Longridge

Marcus is a character who never entirely felt like he got his due. He was always a welcome presence on the team (as was actor Kadiff Kirwan on screen), and despite his own flaws and issues, a real voice of reason, working as the perfect offset to Shirley, Roddy and some of the other members of Slough House.

His very presence on this list is testament to that – there are plenty of characters, even pretty central ones, who didn't make the cut. However, his tragic death at the end of season 4, while shocking and affecting, did mean we missed out on learning more about him and his past, getting to know him on a deeper level beyond his dynamic with other characters.

He is, ultimately, more memorable than Moira, and the way his death has continued to reverberate and carry weight in the show bumps him above her on the list.

13. Hugo Weaving as Frank Harkness

Introduced in season 4, Frank Harkness at first acts as that run's biggest mystery, before coming into focus at the end when it is revealed he is River's father.

The biggest argument against his character is that he has thus far been presented as a bit of a cartoon villain, lacking in any real depth or originality. However, the biggest argument for him is that he's played by Hugo Weaving.

Weaving navigates the road between being utterly magnetic yet hugely threatening at the same time, no mean feat given his fairly insubstantial screen time. We know we'll get to see more of him in season 6, and it does feel like there is still more to delve into with his character, but as of writing he is still already the best full-on villain the show has had to offer thus far, and that shouldn't be ignored.

He's more entertaining to watch than Moira or Marcus, or indeed a number of characters above him on this list. If he just had a bit more development and a more rounded sense of individuality, he would be soaring.

12. Jonathan Pryce as David Cartwright

David was often used more as a plot device than a character in his own right in the show's earlier seasons, a foil to Jackson Lamb and a reason for his behaviour towards River. Despite being played by Jonathan Pryce, one of the show's biggest casting coups, he may not have made this list at all a few years ago.

However, as his arc came into sharper focus in season 4, and he was given more depth, the character became more of a tragic figure, and thus more interesting.

Pryce has excelled at everything he has been given, providing the standout performance on the list so far, as we have seen the character go through the early stages of dementia and his relationship with River has taken on new nuances. This has made him one of the beating hearts of the series, and puts him above his nemesis, Frank.

However, we can't say his entertainment value is higher than some of the other characters on this list, and his earlier lack of development means he is still outside of the top 10.

11. Olivia Cooke as Sidonie Baker

Purely in terms of number of episodes, Olivia Cooke's Sid Baker has appeared in the least of anyone on this list. She was shot in the head at the end of the second ever episode, and has been presumed dead ever since. However, a quick word from Roddy at the end of season 1 suggested there could be more to her apparent death, and she could still be out there.

Now, we know that is the case, as Sid returns in season 6. We won't give anything away about her role in the new run yet, but we can say that as in season 1, Cooke is a very welcome presence, at times feeling as though she was never gone. Her performance is warm and likeable, yet she hasn't lost some of the barbed nature she possessed in season 1. Her dynamic with River is particularly strong, building off their chemistry in the show's first run.

Ultimately, Sid can't go higher on this list at this point, simply because she hasn't made her presence felt enough, and her character isn't so dynamic or original as to make up for that. However, Cooke's performance is strong enough, her role in season 6 is bulky enough, and the character crucial enough to the story as a whole, even during her absence, that she lands in number 11, above some of the more supporting figures.

10. Dustin Demri-Burns as Min Harper

Ah, Min. Poor sweet Min, whose time on the show was cut tragically short in season 2. His relationship with Louisa was one of the show's brightest spots of pure joy in these spies' otherwise quite miserable lives, and it was all excellently played by both Rosalind Eleazar and Dustin Demri-Burns.

Demri-Burns was so charming and fun here, so his leaving stuck in fans' minds in a way few other shorter-term characters have done. Min is the show's biggest loss thus far, and while Demri-Burns's comedy background was clear from the off, his dramatic chops cannot be understated, and they made him someone we could all truly root for.

The trouble is simply that he was killed so early on, and therefore his significance to the show is slightly lessened as time goes on. It's hard to put him above any of our remaining Slow Horses (bar the returning Sid), so he settles in at number 10.

9. Aimee-Ffion Edwards as Shirley Dander

If this ranking was based on likability, Shirley would not be up this high. Thankfully, it's not, and her combative and abrasive behaviour make the character a thrill to watch.

Of all the characters listed thus far, Shirley feels like the most original creation, a figure you'd be hard pressed to find in another series. Admittedly, her bristly nature has meant that she is often defined more by her relationships with the other Slough House members, and kept her a little bit at arm's length in the earlier seasons.

In season 5, we got to know her better, a challenge Aimee-Ffion Edwards was more than up to. As she continued to come to terms with Marcus's death, and tried to maintain her sobriety, we started to understand her more than we have before, even as the show still let Shirley be Shirley – she's not going to become shy and retiring anytime soon, and long may it last.

We have a feeling that Shirley will continue to climb its way up the list as her character gets rounded out and she becomes more of a crucial lynchpin in the Slough House team, but for now she lands above Min, but doesn't break into that upper stratosphere.

8. Saskia Reeves as Catherine Standish

Catherine Standish is the ultimate unsung hero of Slow Horses. Constantly underestimated due to her age, her mild manner and her history of addiction, Standish is really the one who keeps the Slough House ship afloat, is the only one who has a chance of keeping Lamb in check, and often the only one who can see the wood for the trees when it comes to the team's various cases.

She's not just workmanlike though. Sakisa Reeves makes her both a heartfelt and humorous presence, and her complex past makes her a fascinating, complex and original character. Her relationship with Shirley, who also struggles with addiction, was a particular highlight in season 5, and her perpetual exasperation at what goes on around her makes her consistently entertaining.

Ultimately, as an unsung hero, she often has less bombastic or memorable moments than some of the others, accounting for her position below the top seven.

7. Rosalind Eleazar as Louisa Guy

One of the most relatable, pragmatic and down-to-Earth of the Slough House team, Louisa was also one of the most efficient agents, and thrilling to watch in an action set piece. She's not exactly a bundle of light and sunshine, and can certainly be a tough nut to crack, but the fact that she is still so engaging as a character and such a draw is a testament to the show's sharp writing and Rosalind Eleazar's impressively empathetic portrayal.

Her dynamics the likes of with River, Min and Marcus have been some of the best on the show, yet she is also a force in her own right, who we would happily watch go off on her own mission. Sure, she'd grumble along the way, but unlike some of the others we'd understand her gripes – like Standish, she is so often a source of sense in this insane world, something which is sorely needed.

All of this makes her a real contender to head to the top of the list, but admittedly in recent seasons her absence from the series has somewhat diminished her impact. In season 5 she left the Slough House team in the first episode, and while she is set to return in some capacity in season 6, her significance to the show has been blunted by her stop-start appearances and out of the blue departure.

6. Christopher Chung as Roddy Ho

What an utterly loathsome character Roddy Ho is. A man who is utterly solipsistic, completely lacking in empathy and utterly unsuited to being part of a team. That is exactly why he appears as high up as he does on this list. Of course, Christopher Chung manages to imbue him with slightly more likability than could otherwise have been the case, but really the reason we love Roddy is because he's so repulsive and utterly unrepentant, giving him excellent entertainment value.

Most shows in their sixth season would feel the need to make a character as central as Roddy slowly start to develop a heart, to become more palatable to the general audience and show some growth. The fact that Slow Horses refuses to do so, and continues to revel in his refusal to change, is part of why fans embrace the show as much as they do.

This makes him utterly crucial to setting the tone of the series, even if his lack of internal depth does keep him from the top spots.

5. Tom Brooke as JK Coe

JK Coe had a slow start in the series following his introduction in season 4, appearing as a background character with a mildly threatening aura. However, he made his presence known at the end of that run when he nonchalantly killed Patrice, after talking Shirley out of doing so.

Since then, he became one of the shining stars of season 5, with Tom Brook utilising his excellent comic timing to great effect, while also making the character a constant enigma. He is utterly unpredictable but in a quiet, subtle way, in a role which could have been overplayed by another actor.

From every move Brook makes there's a sense that there's more to Coe than meets the eye, and he has already said that he wants to star in an adaptation of a prequel novel exploring the character's murky backstory. All we can see is with a character this original and a performance this entertaining, we're in.

The character's depth means he lands just ahead of Roddy, but if you're looking for entertainment value, there's a character who was introduced at the same time as him who somehow manages to outdo him.

4. James Callis as Claude Whelan

Likely the most controversial placement on this list, some fans may be a bit baffled by Claude's ranking here. He is certainly the least crucial character when it comes to the show's success in the top 5, perhaps even the top 10. However, on all other metrics, Claude scores like gangbusters.

Claude's entertainment value is off the charts, in large part down to James Callis's terrific comic timing and delivery. His dynamic with Taverner is absolutely delicious, and while he feels like a totally original creation, he is also expertly observed.

Most people will know someone like Claude in their life, someone who is not necessarily a bad person, but a flawed and incompetent one, someone who is so out of their depth that it becomes actively aggravating, and even dangerous.

As the show's funniest character, Claude clocks in at number 4. He just couldn't possibly beat Diana Taverner to the punch - not again.

3. Kristin Scott Thomas as Diana Taverner

Kristin Scott Thomas's Diana Taverner is the most crucial ingredient to the show's success listed thus far, adding a fundamental level of tension to proceedings while also being that rare thing in the world of Slow Horses – she is, for the most part, pretty efficient and good at her job. Of course, "good" is an arguable term here.

Taverner is in no way an agent of rectitude, but someone who sees the world in all of its shades of grey, and will certainly act in the interest of the country and the agency – just not, necessarily, before her own interests. The fact that we don't see as much of her across the series only makes her more intriguing.

We can never quite know what she's thinking, in part thanks to Scott Thomas's brilliantly cutting portrayal, and that makes her that rare character where you never quite know what she's going to do next. It's thrilling to watch, meaning she lands near the very top of the list, even if she can't dethrone the show's two most central characters.

2. Gary Oldman as Jackson Lamb

It's pretty inarguable that Slow Horses would be anywhere near the hit that it is without either Gary Oldman or his take on Herron's most recognisable character, Jackson Lamb. Across the six seasons thus far, Oldman has completely embodied that role, and it's always been clear, perhaps more than anyone, just how much fun he's having here. The character is a brilliant combination of at once being an enigma, with a past we only ever see glimpses of or find out about piecemeal, yet also being so brazen, so brash, so out in the open with all of his flaws.

Like with Roddy Ho, Jackson is not a character who is looking for redemption, or who we are likely to see 'change his ways' anytime soon. Even his small moments of kindness or open humanity, such as securing Marcus's salary for his family or having a drink with River at the end of season 4, are couched in barbs and hostility. Perhaps the best thing about Lamb, beyond being one of the funnier characters on the show while also carrying a sense of darkness, is that you always sense he has an ace up his sleeve and a plan in place – you just don't know what that plan is, or how it will impact the others.

All this to say, Jackson is easily the most original character the show has to offer, and the most crucial to its success (thus far). To have him any lower on this list would be criminal. Even not ranking him at number one will be contentious, but there is one character who pips him to the post.

1. Jack Lowden as River Cartwright

The final two placings of this list were on a knife edge. Could we really put someone who isn't Jackson Lamb at the top?

It turns out, yes, we absolutely can, because River is the best character in Slow Horses history. His dynamic with Lamb may ultimately be the show's secret sauce, meaning it wouldn't work nearly as well without both of them and their duelling personalities but, the reason River heads to the top of this list is his humanity.

Lamb is endlessly fascinating, hilarious and a bundle of quirks and characteristics, but River shoulders the emotional burden of the series – the whole show relies on us engaging with him on a deeper level, and succeeds because we really do.

Because of this, it can often be underestimated just how funny River can be, how entertaining he is both in action sequences and in back and forth discussions. He may be the straight-man to Lamb's comedian, but he is not a cut and dry action hero. Instead, he's deeply flawed, egotistical and often reckless, yet someone we root for all the same.

Jack Lowden is fantastically well-cast, and has been getting better in the role with each season. It's easy to see why those rumours have been swirling that he could play Bond, but quite frankly, he's already played a more endlessly engaging character in River. In the battle of the Slow Horses characters, he takes the crown.

Slow Horses is available to stream on Apple TV. Season 6 will be released from 16 September. Start your seven-day free Apple TV trial.

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