All 126 actors in both ER and Star Trek: Enterprise
126 actors have appeared in both ER and Star Trek: Enterprise, across 429 episodes. The most-credited is Leland Orser, Dr. Lucien Dubenko in ER and Loomis (21st century) in Star Trek: Enterprise.
| Actor | In ER | In Star Trek: Enterprise | Eps | Eps |
|---|---|---|---|---|
| Leland Orser | Dr. Lucien Dubenko | Loomis (21st century) | 61 | 1 |
| Michelle C. Bonilla | Paramedic Christine Harms | Bu'kaH | 58 | 1 |
| Vaughn Armstrong | Greg Mitchell | Admiral Maxwell Forrest, Kreetassan Captain, Captain Maximilian Forrest (Mirror Universe) | 1 | 18 |
| Randy Oglesby | PICU Doctor | Degra, Trena'L | 1 | 11 |
| Steven Culp | Dave Spencer, Dr. Charles Cameron | Major J. Hayes | 5 | 5 |
| Paula Malcomson | Meg Riley | Madeline Reed | 8 | 1 |
| Clancy Brown | Dr. Ellis West | Zobral | 7 | 1 |
| Daniel Dae Kim | Ken Sung | Corporal D. Chang | 4 | 3 |
| Eric Pierpoint | Mr. Dwyer | Harris (Section 31), Shiraht | 1 | 5 |
| Maury Sterling | Dr. Nelson | Tarquin | 5 | 1 |
| Sean McGowan | Food Court Guy | Corporal F. Hawkins | 1 | 4 |
| Scott MacDonald | Ambulance Driver, Detective | Commander Dolim | 2 | 8 |
| Jim Fitzpatrick | Lt. Col. McGreun | Commander Williams | 1 | 4 |
| Lawrence Monoson | Dean Rollins | First Officer Matthew Ryan | 4 | 1 |
| Bill Cobbs | Mr. Bowman | Emory Erickson | 1 | 1 |
| Brad Greenquist | Mr. Butler | Captain Khata'n Zshaar, Rigelian Kidnapper #1 | 2 | 2 |
| Conor O'Farrell | Richard Abbott | Burzaan, D'Jamat | 2 | 2 |
| Corey Mendell Parker | Byron Evers | Paul Mayweather | 1 | 1 |
| Dennis Cockrum | Little League Player's Father | Alien Barkeep | 1 | 1 |
| Efrain Figueroa | Julio Echevarria | Translator Voice (Universal translator) | 1 | 1 |
| Glenn Morshower | Rick Decoyte | MacReady | 1 | 1 |
| Gregg Henry | Officer Mark Downey | Zho'Kaan | 1 | 1 |
| Michael McGrady | Fire Captain Davis | Nausicaan Prisoner (Canamar) | 1 | 1 |
| Wade Williams | Migraine Guy | Garos | 1 | 1 |
| William Utay | Dr. Lassally | Captain Vanik | 1 | 1 |
| Mary Mara | Loretta Sweet | Sphere-Builder Presage | 9 | 3 |
| David Selburg | Dr. Dyer | Vulcan Captain | 2 | 1 |
| Gary Riotto | Cousins | Alien #1 | 2 | 1 |
| Gregory Itzin | Burn Doctor | Admiral Black (Mirror Universe), Captain Sopek | 1 | 2 |
| Josh Drennen | Officer Jones | Thalen (Degra's Assistant) | 1 | 2 |
| Mark Rolston | Officer Thomas | Captain Magh, Kuroda Lor-ehn | 1 | 2 |
| Philip Boyd | Biker | Comm officer | 1 | 2 |
| Thomas Kopache | Dr. Stofsky | The Alien (Test subject), Tos | 1 | 2 |
| John Rubinstein | Dr. Kenner | Minister Kuvak, Mazarite Captain | 1 | 3 |
| Michael Reilly Burke | Dick White | Koss | 1 | 3 |
| Brett Rickaby | Vincent Hales | Yerdrin Lek | 1 | 1 |
| Cullen Douglas | Marvin | Suliban Commander | 1 | 1 |
| D.C. Douglas | Ambrose | Zepht | 1 | 1 |
| Danny Goldring | Tony Logan | Alien Captain, Nausicaan Captain | 1 | 2 |
| David A. Kimball | tbd | Esaak | 1 | 1 |
| David Richards | Henderson, Priest | Dockmaster | 2 | 1 |
| Diane DiLascio | Officer Lisa Kimble | Riaan | 1 | 1 |
| Emily Bergl | Gloria Milton | Bethany | 1 | 1 |
| Franc Ross | Naughton | Grizzled Man (Mirror Universe) | 1 | 1 |
| Henri Lubatti | Victor | Ethan Novakovich | 1 | 1 |
| Jeffrey Dean Morgan | Firefighter Lorcan | Damron | 1 | 1 |
| Joan Pringle | Hyams, Josephine | Rianna Mayweather | 2 | 1 |
| Josette DiCarlo | Mrs. D'Angelo | Sphere-Builder Woman | 1 | 4 |
| Leland Crooke | Bart | Plinn | 1 | 1 |
| Leslie Silva | Sonya Bassett | Danica Erickson | 1 | 1 |
| Mark Moses | Mr. Marks | Henry Archer | 1 | 2 |
| Mary Carver | Matilda | Nadet | 1 | 1 |
| Maximillian Kesmodel | Tommy Santo | Sim-Trip at 4 | 1 | 1 |
| Tim Kelleher | U.S. Embassy Official | Pell | 1 | 1 |
| William Lucking | Kenny Brannigan | Harrad-Sar | 1 | 1 |
| Gregory Wagrowski | Walton, Herm Bullard | Ceris | 3 | 1 |
| Richard Riehle | Mandrake Patient | Jeremy Lucas | 1 | 2 |
| Tommy "Tiny" Lister | Patient | Klaang | 1 | 2 |
| Brigid Brannagh | Jamie Hendricks | Ruby | 1 | 1 |
| Christopher Darga | Wilson | Vorok | 1 | 1 |
| Francis Guinan | Police Negotiator | Gosis | 1 | 1 |
| John Cothran, Jr. | Dennis Gant, Sr. | Gralik Durr | 1 | 1 |
| Karl Wiedergott | Dr. Krepp | Larr | 1 | 1 |
| Laura Putney | Patricia Cox | Trevix | 1 | 1 |
| Michael Krawic | Willow | Stron | 1 | 1 |
| Scott Klace | Chris Halpern | Goff | 1 | 1 |
| Geoff Meed | Bart, Gary Parnell | Dee'Ahn Male | 2 | 1 |
| Lee Arenberg | Juke | Gral (Tellarite) | 1 | 2 |
| Louis Ortiz | Jorge | Klingon Warrior (Crewman: Goroth's starship), Suliban Medic | 1 | 2 |
| Alex Nevil | Mr. Dorset | Menk Man | 1 | 1 |
| Bruce Gray | Carter Board member, Dr. Munch | Surak | 2 | 1 |
| Bruce Wright | George Dunleavy, Pilot Gordon | Fer'at | 2 | 1 |
| Dayo Ade | James Rollins | Klingon Weapons Officer | 1 | 1 |
| Dennis Howard | Dr. Steinman | Vulcan Captain | 1 | 1 |
| Holmes Osborne | Dr. Sayers | Enolian Official | 1 | 1 |
| Jamison Yang | Shuang Tseng | Crewman (Medical technician) | 1 | 1 |
| John Rosenfeld | FBI Agent Robert Clayton | Mark Latrelle | 1 | 1 |
| Keith Szarabajka | Mr. DeLuca | Damrus | 1 | 1 |
| Kevin Brief | Walter Brosnich | Naarg | 1 | 2 |
| Kieran Mulroney | Marty's Father | Shaw | 1 | 1 |
| Michael Garvey | Eddie Paloynski | Captain Goroth | 1 | 1 |
| Ric Sarabia | Drunk | Alien #2 | 1 | 1 |
| Ruth Williamson | Registry Nurse | Sphere-Builder Primary | 1 | 3 |
| Sam Witwer | Tommy | Sloth #3 (Technician #2) | 1 | 1 |
| Scott Burkholder | tbd | Rellus Tagrim | 1 | 1 |
| Billy Mayo | Detective Brannigan, Sheriff | Officer #1 | 2 | 1 |
| Mark Elliott Silverberg | Med Student Urbanus | Kraul | 2 | 1 |
| Tom Wright | Wharton | Ghrath | 2 | 1 |
| Christopher Wynne | Resident | Dr. Moninger | 1 | 1 |
| Connor Trinneer | EMT | Sim | 1 | 1 |
| F.J. Rio | Miguel Rivas | Vissian Chief Engineer | 1 | 1 |
| Jeff Kober | Stuart | Traeg | 1 | 1 |
| Lamont Thompson | Paul GIlliam | ND Alien Pilgrim | 1 | 1 |
| Mark Chaet | Tim | Yolen | 1 | 1 |
| Richard Tanner | Dad | Vulcan Initiate | 1 | 1 |
| Stephanie Erb | Mrs. Kinney | Receptionist | 1 | 1 |
| Vincent Hammond | Gurney Man | Huge Alien | 1 | 1 |
| Matt Williamson | Fireman #1, Ted | Klingon Council Member | 2 | 1 |
| Brian Cousins | Allman | Alien Lieutenant | 1 | 1 |
| Casey Biggs | Mike | Illyrian Captain | 1 | 1 |
| Christopher Goodman | Andrew | Thalen (Degra's Assistant) | 1 | 1 |
| Coleen Maloney | Mrs. Tierny | Vulcan Officer | 1 | 1 |
| Jamie McShane | Josh Rushing | Tactical Crewman | 1 | 1 |
| Ryan Honey | Gary | Guard (Enterprise Brig (2153)) | 1 | 1 |
| Tom Schanley | Detective Middleton | Greer | 1 | 1 |
| Vince Grant | Jeff Woodman | Yarrick | 1 | 1 |
| Barbara Tarbuck | Alice Presley | Chancellor Kalev | 1 | 1 |
| Byron Thames | Willy | Crewman | 1 | 1 |
| Dave Power | Jeremy Cranston | Ensign Jeffrey Pierce | 1 | 1 |
| David Figlioli | Nolan | Klingon Crewman (Weapons officer: Duras' Bird-of-Prey) | 1 | 1 |
| Kate McNeil | Mrs. Pendry | Commander Collins | 1 | 1 |
| Kenneth White | Watson | Engineering crewman | 1 | 1 |
| Patrick Fischler | Chamber Tech | Doctor Mercer | 1 | 1 |
| Carol Abney | Fire Chief Amanda Miller | Seleya crewmember (Unnamed: #4) | 1 | 1 |
| Chris Freeman | Firefighter Deshazo, Oliver Miles | Alien Head Guard (Trellium mines) | 2 | 1 |
| Dell Yount | Mazanski | B'Rat | 1 | 1 |
| Jennifer Williams | Joan | Risan Woman | 1 | 1 |
| John Short | Dr. Schlansky | Drake | 1 | 1 |
| Michael Childers | Thal | Lawrence Strode | 1 | 1 |
| Jordan Orr | Thomas | Young Malik | 1 | 1 |
| Marco Sanchez | O'Connor | Corporal M. Romero | 1 | 1 |
| Christine Romeo | Mother | Susan Khouri | 1 | 1 |
| Joseph Ruskin | Mr. Kingsley | Suliban Doctor | 1 | 1 |
| Donald Sage MacKay | Detective Lash | Shilat | 1 | 1 |
| Josh Cruze | Boss | Captain Ramirez | 1 | 1 |
| Ricky Luna | Baseball Player | Carlos | 1 | 1 |
Cast data from TVmaze, licensed CC BY-SA 4.0.