YMMV / Slow Horses

• Complete Monster:
  • Dame Ingrid Tearney, First Desk of MI5, is a stone-cold schemer who desires the security of her position above all else. Already established as a ruthless leader in Season 1 when she orders the elimination of all witnesses to Hassan Ahmed's false flag kidnapping and has a reporter murdered for seeking the truth, Tearney is revealed to be much worse in Season 3. She tested a volatile, unsanctioned device in Istanbul that would enable her to wirelessly hack any computer system in the world, and when the device malfunctioned and hospitalized dozens of people, Tearney's only concern was covering up her hand in it. After killing MI5 agent Alison Dunn and framing it as a suicide, Tearney later learns that Alison's siblings, as well as her lover Sean, are trying to expose the truth. Tearney responds by ordering the cold-blooded executions of not just Sean and Alison's siblings, but also the entire Slough House team and anyone else in proximity of the truth. Hiding behind platitudes of serving her country, Tearney only values her personal power and is willing to kill anyone to maintain it.
  • Season 1: "Curly" is easily the most unhinged of the quartet of kidnappers calling themselves the "Sons of Albion". With the others, Curly kidnaps a student named Hassan based on his Pakistani ethnicity and announces Hassan will be decapitated on a livestream the following morning, ignoring Hassan's pleas that he was born and raised in Britain. Although the kidnapping is a False Flag Operation and Hassan isn't meant to be in danger, Curly is genuinely intent on killing Hassan so he can graduate from an "armchair soldier" to a real killer. In short order, Curly takes an axe to the face of one of the other Sons after figuring out he's a mole; shoots the other through the face for not wanting to go ahead with the plot; and tries to kill the last one for attempting to help Hassan escape. Curly also comes close to committing a horrific massacre at a gas station just to terrorize Hassan into compliance, in particular promising to make a mother watch as he decapitates her two toddlers, then her.
• Magnificent Bastard:
  • Jackson Lamb is the head of Slough House, who masks a truly dangerous spy beneath his slovenly, lazy exterior. Considered one of MI5's best agents, Lamb took the position at Slough House to escape the constant bloodshed and trickery he was engaging in, most notably fooling the entirety of the Soviet spy network by playing one of their moles. Lamb mocks and derides those in his employ, yet holds genuine care for them that he regularly expresses by saving them from trouble or avenging their untimely deaths. After skillfully evading an attempted frame-up on Slough House by MI5, Lamb helps take down a False Flag Operation and cover up MI5's involvement in it to preserve public peace. Later taking on the return of infamous Russian spymaster "Alexander Popov" and his Cicada sleeper agents, Lamb uses his spies to weed out Cicada agents across London. Confronting "Popov"—aka Katinsky—in-person for a final battle, Lamb reveals he has utterly outdone his foe, leaves him a gun with which to commit suicide, and departs with words of genuine respect for Katinsky's work.
  • Season 2: Nikolai Katinsky created the fictional persona of "Alexander Popov" to mask his true identity as Russia's greatest spymaster during the Cold War. A brilliant machinator with webs extending all over the world in the form of his Cicada sleeper agents, Katinsky was forced into hiding when Lamb ousted one of his moles and soured Katinsky's reputation. Genuinely mournful of the loss of one of his subordinates, Katinsky schemed for years at paying Lamb back, and eventually allies with the corrupt Arkady Pashkin to rob the Glasshouse and humiliate Lamb in one swoop. Katinsky eliminates several MI5 agents with his Cicadas and sends Slough House on several wild goose chases, culminating in fooling them into calling in a false bomb threat to leave the Glasshouse defenseless. Meeting with Lamb for a final confrontation, Katinsky comes within a hair's breadth of killing all of Lamb's allies and solidifying his victory. Even when he's beaten by Lamb, Katinsky stoically chooses to end his own life rather than face prison, having long accepted his death after a cancer diagnosis that sparked his crusade of vengeance.
• Moral Event Horizon: Nick Duffy arguably crosses this when he orders the assault on the storage facility and then murders the socially inept and generally harmless Douglas after he reveals a trivial piece of information that was unlikely to ever be a security threat. Though knowing Duffy, he probably crossed this many times previously in his career. Some viewers may even decide he crossed it when he murdered the sleazy journalist Robert Hobden in the first season.

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