 | Dev Patel als Gawain |
 | Alicia Vikander als Lady / Essel |
 | Joel Edgerton als Lord |
 | Sarita Choudhury als Mother |
 | Sean Harris als King |
 | Kate Dickie als Queen |
 | Barry Keoghan als Scavenger |
 | Erin Kellyman als Winifred |
 | Ralph Ineson als Green Knight |
 | Emilie Hetland als First Thief |
 | Anthony Morris als Second Thief |
 | Megan Tiernan als The Young Queen |
| Helena Browne als Sightless Woman |
 | Brendan Conroy als Taverngoer |
 | Chris McHallem als Lord in Waiting |
 | Atheena Frizzell als Youngest Sister |
 | Donncha Crowley als Bishop |
| Anaïs Rizzo als Helen |
| Joe Anderson als Paris |
| Nita Mishra als Older Sister |
| Tara Mae als Middle Sister |
| Sam Uppal Lynch als Prince Age 7 |
 | Adam Karim als Prince Age 17 |
| Ruth Patel als Princess Age 4 |
| Rose Patel als Princess Age 6 |
| Emmet O'Brien als Magician |
| Andrea Deaskovic als Giant |
| Aoibheann Garry als Giant |
| Isabel Friosi als Giant |
| Hannah Sjoden als Giant |
| Lucy Waters als Giant |
| Melinda Dempsey als Giant |
| Rachel Quinn als Giant |
| Ethan Dillion als Soldier #1 (uncredited) |
| Aaron Edo als Soldier #2 (uncredited) |
 | Youssef Quinn als Soldier #3 (uncredited) |
| Patrick Duffy als Gawain's Friend in Tavern (uncredited) |
| Janet Grene als Townsfolk (uncredited) |
| Tyrone Kearns als Noble (uncredited) |
| Tom Leavey als Knight of the Round Table (uncredited) |
| Noelle Brown als Madam |
| David Lowery | Director |
| Toby Halbrooks | Producer |
| Aaron L. Gilbert | Executive Producer |
| David Lowery | Producer |
| James M. Johnston | Producer |
| Jason Cloth | Executive Producer |
| Louise Kiely | Casting Director |
| Ciara McArdle | Costume Supervisor |
| Giedrius Nagys | Stunt Coordinator |
| Paul Byrne | Special Effects Supervisor |
| Daniel Hart | Original Music Composer |
| Malgosia Turzanska | Costume Designer |
| Tim Headington | Producer |
| Macdara Kelleher | Executive Producer |
| David Lowery | Editor |
| Christine McDonagh | Art Direction |
| Chris Debiec | Production Consultant |
| Theresa Page | Producer |
| Edmund Sampson | Line Producer |
| Andrew Droz Palermo | Director of Photography |
| Joe Howes | Visual Effects |
| Tomas Deckaj | First Assistant Director |
| Chris A. Wilks | Special Effects Coordinator |
| David Kirchner | Post-Production Manager |
| Jessica Brooks | Special Effects Makeup Artist |
| Eileen Buggy | Hair Designer |
| Aisling Nairn | Key Makeup Artist |
| Audrey Doyle | Makeup Designer |
| Davi Aquino | Foley Recordist |
| Christopher Barnett | Sound Re-Recording Mixer |
| Christopher Barnett | Supervising Sound Editor |
| Patrick Christensen | ADR Mixer |
| Jack Heeren | Foley Mixer |
| Goro Koyama | Foley Artist |
| Phil Lawlor | Sound Assistant |
| Johnny Marshall | Sound Designer |
| Johnny Marshall | Supervising Sound Editor |
| Karl Merren | Production Sound Mixer |
| Greg J. Peterson | Sound Effects Editor |
| Eddie Quinn | Boom Operator |
| Kevin Schultz | Foley Mixer |
| Michael Semanick | Sound Re-Recording Mixer |
| Jade Healy | Production Design |
| David Pink | Art Direction |
| Jenny Oman | Set Decoration |
| Kevin Cahill | Visual Effects Supervisor |
| Nicholas Ashe Bateman | Visual Effects Supervisor |
| Roni Rodrigues | Visual Effects Supervisor |
| David Sadler-Coppard | Visual Effects Supervisor |
| Eric Saindon | Visual Effects Supervisor |
| Corinne Clery | Makeup Artist |
| Sonia Dolan | Makeup Artist |
| Clodagh McInerney | Makeup Artist |
| Rey Medrano | Makeup Department Head |
| Sarah O'Brien | Makeup Artist |
| Tina Phelan | Makeup Artist |
| Richard Gould | Sound Effects Editor |
| Richard Gould | Foley Editor |
| Johanny Anderson | VFX Artist |
| Marc Landrain | VFX Artist |
| Christopher Newlove-Carvisiglia | VFX Artist |
| Edmund Sampson | Executive Producer |
| Tomas Deckaj | Executive Producer |
| Eoin Egan | Executive Producer |
| Anjay Nagpal | Co-Executive Producer |
| Ashley Levinson | Co-Executive Producer |
| Jeanie Igoe | Co-Producer |
| Karen Scully | Casting Associate |
| Philippe Zone | Stunts |
| Paul Thompson | Stunts |
| Stephen Ryan | Stunts |
| Donal O'Shea | Stunts |
| Michelle O'Loughlin | Stunts |
| Eimear O'Grady | Stunt Coordinator |
| Erol Ismail | Stunt Double |
| Michael Hanna | Stunts |
| Jessica Grant | Stunts |
| Sophie Doyle | Stunt Double |
| Yusuf Chaudhri | Stunt Double |
| Aoife Byrne | Stunts |
| David Lowery | Writer |
| Emma Moffat | Makeup Artist |
