A young, hot-tempered MI5 officer exiled to Slough House after a botched training exercise. Determined to restore his reputation, he proves the most driven of the slow horses, pulling the team into dangerous investigations. He is also the grandson of legendary former intelligence officer David Cartwright, whose past threatens them both.
Collins is a Royal Air Force Spitfire pilot flying alongside Farrier during the defense of the evacuation. After his aircraft is hit while protecting a minesweeper, he is trapped underwater until Peter rescues him, and he later parts from the Dawsons after reaching safety.
An English nobleman sent to Scotland under false pretenses who becomes Mary’s husband. His presence triggers political crises, he is involved in Rizzio’s murder, and after a failed escape and banishment, he is ultimately assassinated by the Earl of Bothwell.
Nikolai Rostov is Natasha Rostova's older brother, and he joins the Imperial Russian Army immediately as the conflict approaches Russia. The war helps him mature, while his romantic life is complicated by his childhood love for Sonya Rostova and pressure from his impoverished parents to marry a rich bride.
Zak is Saraya’s brother and a young wrestler who applies for WWE alongside her. Although Hutch refuses to sign him, Zak’s anger and disappointment challenge Saraya when she considers quitting. His confrontation with her ultimately pushes her to reclaim her ambition and return to training.
Ryan Newell is Ella's husband, whose relationship with her becomes the source of a political scandal. He leaks information about their encounters, bribes a reporter, demands a government position, threatens Ella's reputation, and publicly blames her for their separation after she refuses to submit.
Little Sugar is Sugarman’s son and a member of his violent gang. He spots Tornado after she escapes into the hills and later confronts his father over a lifetime of bullying and their growing hostility. After secretly killing Kitten, he attacks Sugarman, who stabs him to death.
Thommo is a British soldier who pursues the stolen rifle with Gary Hook after the crowd turns violent. The two soldiers are beaten and disarmed by the mob, but Thommo is then shot dead at close range by Paul Haggerty, leaving Hook alone and hunted in Belfast.
Childhood friend of Marcus who goes hunting in the Scottish Highlands. Accidentally shoots a boy, leading him and Marcus to cover it up. Captured by the community, he is forced by Logan to kill Marcus to save himself. Months later, he remains deeply traumatized while awaiting the birth of his child.
Siegfried Sassoon is the central figure, a soldier and poet whose wartime service leaves him wounded, traumatized, and morally horrified. After receiving the Military Cross, he protests the decision to prolong the war and refuses further duties. His guilt, grief, relationships, and struggle to survive memory drive the narrative.
The introverted, sullen protagonist growing up in 1970s Manchester. He is a loner who writes letters and reviews for music newspapers while struggling to choose between his father's practical expectations and his mother's encouragement to pursue writing. He experiments with songwriting and singing but faces repeated setbacks until guitarist Johnny Marr arrives at his door in 1982.
Thomas is Ben's stepbrother and one of the people who takes responsibility for caring for Charlotte after Ben's death. He remains with Charlotte in the family's old manor while she awaits the baby's arrival, but her growing unease causes her to suspect that his apparent concern may conceal less benevolent intentions.
Jack Lowden has 36 screen credits in a career dating back to 2007. Signature works include Slow Horses, Mary Queen of Scots, Fighting with My Family. Explore the interactive character relationship maps on each title page to trace how their roles connect across franchises.
