Vo filme O 28 dní... hrajú Cillian Murphy (Jim), Naomie Harris (Selena), Brendan Gleeson (Frank), Megan Burns (Hannah), Christopher Eccleston (Major Henry West), Noah Huntley (Mark), Luke Mably (Private Clifton), Stuart McQuarrie (Seargent Farrell), Ricci Harnett (Corporal Mitchell), Leo Bill (Private Jones), Junior Laniyan (Private Bell), Ray Panthaki (Private Bedford), Sanjay Rambaruth (Private Davis), Marvin Campbell (Private Mailer), Christopher Dunne (Jim's Father), Emma Hitching (Jim's Mother), Alex Palmer (Activist), Bindu De Stoppani (Activist), Jukka Hiltunen (Activist), David Schneider (Scientist), Alexander Delamere (Mr. Bridges), Kim McGarrity (Mr. Bridges' Daughter), Toby Sedgwick (Infected Priest), Justin Hackney (Infected Kid), Adrian Christopher (Featured Infected), Richard Dwyer (Featured Infected), Nick Ewans (Featured Infected), Terry John (Featured Infected), Paul Kasey (Featured Infected), Sebastian Knapp (Featured Infected), Nicholas James Lewis (Featured Infected), Jenni Lush (Featured Infected), Tristan Matthiae (Featured Infected), Jeffrey Rann (Featured Infected), Joelle Simpson (Featured Infected), Al Stokes (Featured Infected), Steen Young (Featured Infected).