All 69 actors in both Once Upon a Time and The 100
69 actors have appeared in both Once Upon a Time and The 100, across 256 episodes. The most-credited is Jarod Joseph, Billy, Gus in Once Upon a Time and Nathan Miller in The 100.
| Actor | In Once Upon a Time | In The 100 | Eps | Eps |
|---|---|---|---|---|
| Jarod Joseph | Billy, Gus | Nathan Miller | 8 | 66 |
| Sean Maguire | Robin Hood | Russell Lightbourne | 33 | 3 |
| John Pyper-Ferguson | Kurt Flynn | Bill Cadogan | 1 | 10 |
| Olivia Steele-Falconer | Violet | Young Octavia | 8 | 1 |
| Chris Shields | Military Advisor | David Miller | 1 | 11 |
| Lee Majdoub | Sir Kay | Nelson / Sachin | 1 | 10 |
| Ty Olsson | Hordor | Nyko | 1 | 10 |
| Kendall Cross | Katie | Major Byrne | 1 | 8 |
| Jonathan Whitesell | Hercules | Bryan | 1 | 10 |
| Toby Levins | Sergeant | Carl Emerson | 1 | 10 |
| Paul Lazenby | Claude, Black Knight No. 1, Mirror-Carrying Knight | Rockline Warrior, Sidekick | 4 | 4 |
| Adam Lolacher | Black Knight #2 | Jeremiah | 1 | 8 |
| Karen Holness | Witch of the North | Blythe Ann Workman | 1 | 10 |
| Max Montesi | Peasant Boy | Lindo the Defector | 1 | 6 |
| Nick Hunnings | Peasant, Prison Guard | Lee | 2 | 4 |
| Aleks Paunovic | Berkley | Gustus | 1 | 4 |
| Chad Rook | Captain Ahab | Hatch | 1 | 3 |
| Manny Jacinto | Quon | Boy #1, Boy Bullied by Murphy | 1 | 2 |
| Sharon Taylor | Witch of the East | Council Member #2 | 1 | 4 |
| Greyston Holt | Jim/Frederick | Gavin / Marcus Kane II | 2 | 2 |
| Mark Gibbon | Head Troll | Grounder #1 / Bounty Hunter | 2 | 2 |
| Giacomo Baessato | Grif, Sleeping Man | Diggs | 2 | 1 |
| Milli Wilkinson | Young Cruella | Young Echo | 1 | 2 |
| Nicole Muñoz | Young Lily | Lucy | 2 | 1 |
| Tristan Jensen | Horatio | Captain Sea Grounder | 1 | 2 |
| Catherine Lough Haggquist | Fairy Godmother | Council Member #1 | 1 | 3 |
| Nisreen Slim | Doctor Andrea Sage | Grounder Mother / Dying Woman | 2 | 2 |
| Alex Barima | Twin #1 | Kwame | 2 | 3 |
| Dalias Blake | Palace Guard | Other Tech | 1 | 1 |
| Darren Moore | Vortigan | Orlando | 1 | 2 |
| Jesse Hutch | Peter | Lead COG | 1 | 1 |
| Zak Santiago | Prince Henry | Semet | 1 | 2 |
| Ian Butcher | Burly Knight | Bryson | 1 | 3 |
| Primo Allon | Gadling | Chief Guard | 1 | 2 |
| Teach Grant | Dead Eye | Cuyler Ridley | 1 | 2 |
| Corey Schmitt | Second Mate | Prisoner #2 | 1 | 1 |
| Rick Dobran | Raskind | Merchant | 1 | 1 |
| Garfield Wilson | Guard | Soldier | 1 | 3 |
| Quinn Lord | Josef/Hansel | Young Member of the 100 | 1 | 1 |
| Artine Brown | Arresting Cop | Lt. Graco | 1 | 2 |
| Mik Byskov | Black Knight Archer | Otan | 1 | 2 |
| Rohan Campbell | Male Miner | Dave | 1 | 2 |
| Dalila Bela | Young Guinevere | Leigh | 1 | 1 |
| Darcy Laurie | Louie | Tybe | 1 | 1 |
| Glynis Davies | Spinster #2 | Elderly Azgeda Woman | 1 | 1 |
| Matt Kennedy | Boyfriend | Jacov | 1 | 1 |
| Patrick Roccas | Arendelle Guard #2 | Azgeda Scout | 1 | 1 |
| John DeSantis | The Dove | Gideon | 1 | 2 |
| Andre Tricoteux | Argyle, Massive Brawler | War Chief #3 | 2 | 1 |
| Arpad Balogh | Eric's Footman | Shield Guard Patrol #1 | 1 | 1 |
| Bart Anderson | Innkeeper | Griff | 1 | 1 |
| J.C. Williams | Lead Guard | Lead Guard | 1 | 1 |
| Jennifer Cheon | Nurse | Dakiva | 1 | 1 |
| Jennifer Koenig | Queen of Hearts | Wailing Woman | 1 | 1 |
| Sean Owen Roberts | Ruffian | Wayne Szybunka | 1 | 1 |
| Craig Erickson | Butler | Arker Man | 1 | 1 |
| Graem Beddoes | Gruff Patron | Harris | 1 | 1 |
| Ian Nsenga | First Mate | Dead Male Defector | 1 | 1 |
| Lee Tichon | Guard | Pike's Guard | 1 | 1 |
| Jim Shield | Royal Guard | Grounder Warrior #1 | 1 | 1 |
| Michael Strusievici | Little Fairy Tale Boy | Gavriel | 1 | 1 |
| Naiah Cummins | Uniformed Police | Lead Disciple | 1 | 1 |
| Spencer Drever | boy | Young Bellamy | 1 | 1 |
| Chad Riley | Black Knight #2 | Osias | 1 | 1 |
| Jesse Stretch | Head Viking | Huge Wonkru Man | 1 | 1 |
| Ryan Hesp | Quartermaster | Man | 1 | 1 |
| Charles Zuckermann | Black Knight #1 | Grizzled Warrior | 1 | 1 |
| Jason Cermak | Black Knight #1 | Hull | 1 | 1 |
| Michael Adamthwaite | Alistair | Reaper | 1 | 1 |
Cast data from TVmaze, licensed CC BY-SA 4.0.