All 79 actors in both Smallville and The 100
79 actors have appeared in both Smallville and The 100, across 317 episodes. The most-credited is Alessandro Juliani, Dr. Emil Hamilton in Smallville and Jacapo Sinclair in The 100.
| Actor | In Smallville | In The 100 | Eps | Eps |
|---|---|---|---|---|
| Alessandro Juliani | Dr. Emil Hamilton | Jacapo Sinclair | 14 | 20 |
| Sarah Jane Redmond | Nell Potter | Kaylee Lee | 11 | 5 |
| Mike Dopud | Security Guard George | Michael Vinson | 10 | 5 |
| Alaina Huffman | Dinah Lance / Black Canary | Nikki | 6 | 8 |
| Erica Cerra | Adrianna Tomaz, Lex's Aid, Sorority Girl | Alie, Becca Franko | 3 | 21 |
| John Pyper-Ferguson | Dr. William McBride | Bill Cadogan | 1 | 10 |
| Sharon Taylor | Faora | Council Member #2 | 7 | 4 |
| Hiro Kanagawa | Principal H. James Kwan | Council Member #3 | 5 | 4 |
| Rekha Sharma | Dr. Harden | Lorelei Tsing | 7 | 9 |
| Chris Shields | Courier, EMT #1, Reporter | David Miller | 4 | 11 |
| Colin Lawrence | Agent Stocker, Captain Nichols, Doctor | Rivo | 3 | 2 |
| Ian Tracey | Lincoln Cole | Vincent Vie | 1 | 3 |
| JR Bourne | Dr. Bernard Chisholm | Russell Lightbourne VII | 1 | 10 |
| Ty Olsson | Officer Talbert | Nyko | 1 | 10 |
| Gwynyth Walsh | Mrs. Moore | Josephine Lightbourne VII | 1 | 2 |
| Kendall Cross | Jessica Kent, Lara-El, Little Girl's Mother | Major Byrne | 3 | 8 |
| John DeSantis | Male Zoner, Solomon Grundy, The Traveler | Gideon | 3 | 2 |
| Britt Irvin | Courtney Whitmore / Stargirl | Alyssa | 4 | 3 |
| Aleks Paunovic | Orderly, Thug #1 | Gustus | 2 | 4 |
| Monique Ganderton | Alia | Aurora Blake | 4 | 2 |
| Christine Willes | Granny Goodness | Vera Kane | 4 | 3 |
| Jonathan Scarfe | Robert Queen | Conductor Doucette | 1 | 4 |
| Paul Lazenby | Tony | Rockline Warrior, Sidekick | 1 | 4 |
| Terry Chen | Detective Paul Cage | Cmdr. Shumway | 1 | 4 |
| Dean Marshall | Seattle Police Officer | Jae Workman | 1 | 10 |
| Greyston Holt | Tobias Rice | Gavin / Marcus Kane II | 1 | 2 |
| James Michalopolous | Carjacker, Prisoner | Fio | 2 | 4 |
| Quinn Lord | Phillipe Lamont | Young Member of the 100 | 2 | 1 |
| Karen Holness | Jessica Bishop | Blythe Ann Workman | 1 | 10 |
| Carlo Marks | Chloe's Fiancé, Stephen Swift | Cillian | 2 | 2 |
| Dean Redman | Lab Guard, Police Officer, Policeman | Guard | 3 | 1 |
| Tom Stevens | Clayton | Trey | 1 | 8 |
| Bart Anderson | Drunk | Griff | 1 | 1 |
| Bradley Stryker | Deadshot | Baylis | 2 | 2 |
| Dalias Blake | Security Guard | Other Tech | 1 | 1 |
| Jesse Hutch | Troy Turner, Billy Durden | Lead COG | 3 | 1 |
| Sean Millington | Luthor Security Guard, Military police | Alpha Reaper | 2 | 1 |
| Steve Bacic | Garage Worker, Vordigan / Dark Archer | Grounder | 2 | 1 |
| Mark Gibbon | Mr. Raines, Orderly, SWAT Commander | Grounder #1 / Bounty Hunter | 3 | 2 |
| Jim Shield | James Gibson, Sylvester Pemperton / Star-Spangled Kid | Grounder Warrior #1 | 2 | 1 |
| Michael Adamthwaite | Andrew Connors, Rick | Reaper | 2 | 1 |
| Michael Rogers | Agent Black | Denby | 1 | 2 |
| Zak Santiago | Deputy Morales | Semet | 1 | 2 |
| Brad Kelly | Thug #3 | Lead Grounder, Harris, Kodiak | 1 | 4 |
| Glenn Ennis | Metropolis Police Officer | Ryder, Machete | 1 | 4 |
| Eric Breker | Roy Rothman | Sgt. Lovejoy | 1 | 1 |
| Ben Cotton | Paul Hendrix | Red | 1 | 2 |
| Catherine Lough Haggquist | Mary | Council Member #1 | 1 | 3 |
| Andrew Francis | William Taylor | Boy in Mask | 1 | 1 |
| David Coles | Scott Bowman | Kuba | 1 | 1 |
| Doug Chapman | Deputy | Big Arker | 1 | 1 |
| Emy Aneke | Robert Pontius | Mt. Weather Soldier #1 | 1 | 1 |
| Tristan Jensen | Police Officer | Captain Sea Grounder | 1 | 2 |
| Christian Sloan | Ben | Ambassador Uzac | 1 | 3 |
| Lucia Walters | Belinda Jenkins | Miranda Mason | 1 | 4 |
| Colin Foo | Card Player | Pei Chao | 1 | 1 |
| Darryl Scheelar | Assassin | Sonic Driller | 1 | 1 |
| Mike Klemak | Police Officer | Guard | 1 | 1 |
| Olivia Steele-Falconer | Natasha | Young Octavia | 1 | 1 |
| Peter Flemming | Brady | Mark Colton | 1 | 1 |
| Todd Mann | Twin #2 | Lead Guard | 1 | 1 |
| Wesley MacInnes | Cameron Mahkent / Icicle | Derek | 1 | 1 |
| Elfina Luk | Female Gangbanger | Rankin | 1 | 2 |
| Ally Kaczynski | Dora | Dead Female Defector | 1 | 1 |
| Chelah Horsdal | Dr. McCann | Simone Lightbourne | 1 | 1 |
| Glynis Davies | Mrs. Palmer | Elderly Azgeda Woman | 1 | 1 |
| Jeremy Jones | Henry's Father | Robert | 1 | 2 |
| Link Baker | Pilot | Ice Nation Ambassador | 1 | 1 |
| Michael Benyaer | Jameson | Zahir | 1 | 1 |
| Michael Jonsson | Agent | Esop | 1 | 1 |
| Suzanne Ristic | Maureen Kenderson | Woman | 1 | 1 |
| Birkett Turton | Jeff Palmer | Apprentice | 1 | 1 |
| Fulvio Cecere | Swim Coach Rick Varley | Inspector Grus | 1 | 1 |
| Jaeson Lee | Neutron | Tomac | 1 | 1 |
| Patrick Keating | Dr. Heller | Groundskeeper | 1 | 1 |
| Noah Dalton Danby | Bouncer | Ivon | 1 | 1 |
| Kaare Anderson | Ramierez | Man | 1 | 1 |
| Gardiner Millar | FBI Agent | Scarfaced Grounder | 1 | 1 |
| Phillip Mitchell | Guard | Large Prisoner | 1 | 1 |
Cast data from TVmaze, licensed CC BY-SA 4.0.