Ralph Fiennes as Dr. Ian Kelson

Jack O'Connell as Sir Lord Jimmy Crystal

Alfie Williams as Spike / Jimmy

Erin Kellyman as Jimmy Ink

Chi Lewis-Parry as Samson

Emma Laird as Jimmima

Connor Newall as Jimmy Shite

Maura Bird as Jimmy Jones

Ghazi Al Ruffai as Jimmy Snake

Robert Rhodes as Jimmy Jimmy

Sam Locke as Jimmy Fox

Gareth Locke as Hunter

Celi Crossland as Pregnant Infected

Mirren Mack as Cathy

Gordon Alexander as Jonno

Louis Ashbourne Serkis as Tom

David Sterne as George

Elliot Benn as Matthew

Lynne Anne Rodgers as Jane Ji

Sebastian Williams-Barrow as Samson (Child)

Natalie Cousteau as Ticket Inspector

Maiya Eastmond as Sam

Cillian Murphy as Jim (uncredited)

Mia Verity as Train Passenger (uncredited)