All 210 actors in both NCIS and The X-Files
210 actors have appeared in both NCIS and The X-Files, across 726 episodes. The most-credited is Mitch Pileggi, U.S. Secretary of Defense Wynn Crawford in NCIS and Assistant Director Walter Skinner in The X-Files.
| Actor | In NCIS | In The X-Files | Eps | Eps |
|---|---|---|---|---|
| Mitch Pileggi | U.S. Secretary of Defense Wynn Crawford | Assistant Director Walter Skinner | 2 | 70 |
| Joe Spano | Tobias C. Fornell | Mike Millar | 56 | 2 |
| Alan Dale | Tom Morrow | Toothpick Man | 16 | 4 |
| Brian Thompson | Master Chief Vince Nutter | Bounty Hunter | 1 | 9 |
| Melinda McGraw | Diane Sterling | Melissa Scully | 6 | 4 |
| Mimi Rogers | CIA Officer Joanna Teague | Agent Diana Fowley | 3 | 6 |
| Susanna Thompson | Army Lt. Col. Hollis Mann | Michelle Generoo | 8 | 1 |
| John Finn | Marine Commandant Charles T. Ellison | Michael Kritschgau | 3 | 5 |
| Elayn J. Taylor | Odette Malone | Nurse #2 | 5 | 1 |
| Roger Cross | Lt. Cmdr. David Warfield | Field Agent, Officer Wentworth, Private Kittel | 1 | 4 |
| Adam Baldwin | Cdr. Rainer | Knowle Rohrer | 1 | 6 |
| Catherine Dent | Former NCIS Special Agent Whitney Sharp | June Gurwitch | 2 | 1 |
| Don S. Davis | MTAC Control Officer | Captain William Scully | 1 | 2 |
| Don Swayze | Logan Clay, Pete Walker | Terry Pruit | 2 | 1 |
| Doug Savant | Larry Clannon, Marine Brigadier General Daniel Kent | Augustus Goldman | 2 | 1 |
| Jack McGee | Det. Floyd, Richard "Rick" Jordan | Bob Damphouse | 2 | 1 |
| James Morrison | CIA Assistant Director Jonathan Overmeier, U.S. Senator John Phillips | Dr. Robert Wieder | 2 | 1 |
| Nick Chinlund | Detective Steve Rosetti | Donald Eddie Pfaster | 1 | 2 |
| Terry O'Quinn | Colonel Will Ryan | Lieutenant Brian Tillman, Shadow Man | 1 | 2 |
| William Devane | Nicolas Mason | General Mark A. Suveg | 1 | 2 |
| Peter Kelamis | Bruce Johnson | Assistant D.A. Daniel Costa, Husband #2, Lieutenant Foyle | 1 | 4 |
| Eric Nenninger | Navy Corpsman Taylor Henley | Jared Chirp | 1 | 1 |
| Karri Turner | Micki Kaydar | Tara Scully | 2 | 2 |
| Lance Henriksen | Sheriff Clay Boyd | Frank Black | 1 | 1 |
| Lily Tomlin | Penelope Langston | Lyda | 1 | 1 |
| Mark Rolston | George Westcott | Bud LaPierre, Richard Odin | 2 | 2 |
| Mark Sheppard | Young Mr. Pain | Bob the Caretaker / Cecil L'Ively | 1 | 1 |
| Michael O'Neill | Former NCIS Special Agent Riley McCallister | Patrol Captain | 3 | 1 |
| Perrey Reeves | Wendy Miller | Kristen Kilar | 1 | 1 |
| Rodney Rowland | Operations Officer Jonah McGuire | Ed Jerse | 1 | 1 |
| Samaire Armstrong | Melissa Goodman | Natalie Gordon | 1 | 1 |
| Stacy Haiduk | Melissa Dorn | Maggie Waterston | 1 | 1 |
| Titus Welliver | Navy Capt. Roger Walsh | Doug Spinney | 1 | 1 |
| Vernée Watson | Miss Helen Frimkes | Nurse Whitney Edwards | 1 | 1 |
| William O'Leary | Chief Martin Freydano | Gas Station Man | 1 | 1 |
| Brian Markinson | Marine EOD Sgt. Dan Trask | Gary Lambert, Tony Fiore | 1 | 2 |
| Chad Lindberg | Joey Peanuts | Bobby Rich | 2 | 1 |
| Debra Christofferson | Rita Gregg, Uta | Pat Verlander | 2 | 1 |
| Denise Crosby | Secretary of the Navy Hattie Taylor | Dr. Mary Speake | 1 | 2 |
| Fredric Lehne | Captain Graves | Arthur Dales | 1 | 2 |
| Kirk B.R. Woller | Lt. Commander Julius | Agent Gene Crane | 1 | 5 |
| Matthew Glave | Navy Commander John McGee | FBI Prosecutor Kalembrenner | 1 | 2 |
| Penny Johnson Jerald | Joanne Torrence | Dr. Hellura Lyle | 2 | 1 |
| Suleka Mathew | Navy Commander Maria Castro | Agent Linda Caleca, Lisa Dole | 1 | 2 |
| Valarie Pettiford | Sonia Eberhart | FBI Agent | 2 | 1 |
| Jay Acovone | Frankie Dean | Duffy Haskell, Det. Joe Curtis | 1 | 3 |
| Sal Landi | Bill Zaprowski, Cmdr. Stovic | Agent Landau, Nicholas Regali | 2 | 2 |
| Bellamy Young | ATF Agent Melinda Stone | Janet Wilson | 1 | 1 |
| Bobby Moynihan | Woodrow "Woody" Browne | Paramedic | 1 | 1 |
| CCH Pounder | Jefferson Parish Coroner Doctor Loretta Wade | Agent Lucy Kazdin | 2 | 1 |
| Chris Ellis | Gunnery Sgt. John Deluca | Sheriff Lance Hindt | 1 | 1 |
| Christopher Allport | Metro Police Cpt. Dan Karzin | Agent Jack Willis | 1 | 1 |
| Christopher Stapleton | Lt. Wade | Guard #1, Pilot | 1 | 4 |
| Dean Norris | Vestman | U.S. Marshal Tapia | 1 | 1 |
| Deborah Strang | Diane Warner | Detective B.J. Morrow | 1 | 1 |
| Gabrielle Miller | Andrea Mavrey | Brenda J. Summerfield, Paula Gray | 1 | 2 |
| George Gerdes | Field Marshall Nigel Rand | Reverend Calvin Hartley | 1 | 1 |
| Glenn Morshower | Cmdr. Robert Peters | Aaron Starkey | 1 | 1 |
| Jamie McShane | Samuel Hayes | Injured Soldier | 1 | 1 |
| Jason Beghe | Blake Martin | Ranger Larry Moore | 1 | 1 |
| Jason Gray-Stanford | Dr. Jay Berman | Officer Eggers | 1 | 1 |
| Jim Beaver | Captain Tom O’Rourke | Coroner | 1 | 1 |
| Joe Nieves | Justin Kinneman | Barreiro's Son | 1 | 1 |
| Judson Mills | Mr. Rasmussen | Deputy Keith Wetzel | 1 | 1 |
| Kate McNeil | Commander Green | Nan Wieder | 1 | 1 |
| Leon Russom | Grandpa | Detective Miles | 1 | 2 |
| Louis Ferreira | Harlan Atwood, Metro Detective Nick Burris | Detective Costa | 2 | 1 |
| Marcus Giamatti | Victor Tillman | John Gillnitz | 1 | 1 |
| Michael Welch | Kody Meyers | Trevor | 1 | 1 |
| Nasser Faris | Arash Kazmi | Silk Shirt Man | 2 | 1 |
| Nestor Serrano | NSA Supervisor Jeremy Marlens | Ken Naciamento | 1 | 1 |
| Patrick St. Esprit | Navy Commander Weidman | Guard #2 | 1 | 2 |
| Robert Curtis Brown | Gary Tolin | Assistant DA Damon Kaylor | 1 | 1 |
| Sam Anderson | Walter Carmichael | U.S. Attorney Leamus | 1 | 1 |
| Spencer Garrett | Commander Spenser | Harry Bring | 1 | 1 |
| Stephen Mendel | Retired NCIS Special Agent Fred Pettis | Dark-Suited Man #2 | 1 | 2 |
| Tracy Middendorf | Tara Bick | Gracie | 1 | 1 |
| Ty Olsson | Burke | Younger Orderly | 1 | 1 |
| Vik Sahay | Ajay Khan | Gupta | 2 | 1 |
| Michael B. Silver | Nicholas Sandlock | Howard Grodin | 1 | 2 |
| Michael Ensign | Doctor Ishmael Havana | Dr. Barnes | 1 | 2 |
| Michael Shamus Wiles | Jimmy the Bartender | Black-Haired Man | 1 | 2 |
| Steven Anderson | Professor Daniel Redner | Dr. James Parenti | 1 | 2 |
| Alex Carter | Knox Elicott | Chief Strong | 1 | 1 |
| Alyson Reed | Monica Keogh | Maggie Lupone | 1 | 1 |
| Anthony Heald | Guyman Purcell | Harold Piller | 1 | 1 |
| Carl Lumbly | Navy Rear Admiral Beau Hindley | Marcus Duff | 1 | 1 |
| Chad E. Donella | John Briggs | Rob Roberts | 1 | 1 |
| Chet Grissom | Rupert Kittridge | Detective | 1 | 1 |
| Conor O'Farrell | William Danforth | Sheriff Ciolino | 1 | 1 |
| Erick Avari | Col. Dan McClafferty | Dr. Herb Fountain | 1 | 1 |
| Gary Grubbs | Coroner Elmo Poke | Sheriff Tom Arens | 1 | 1 |
| Graham Shiels | Martin Jansen | Night Watchman | 1 | 1 |
| Jennifer Hetrick | Dr. Donna Dunlap | Sharon Skinner | 1 | 1 |
| Jillian Bach | Emily Moss | Maggie | 1 | 1 |
| John Kapelos | Vice Principal Vic Castor | Agent Fordyce | 1 | 1 |
| Michael Chieffo | Randy Devereaux | Carl Wade | 1 | 1 |
| Michael Cram | ATF Special Agent Earl Kitt | Officer Corning | 1 | 1 |
| Michael McGrady | Walter Dunn | Sheriff Kurt Frey | 1 | 1 |
| Rebecca Wisocky | Jody Carvell | Jackie Goldman | 1 | 1 |
| Richard Ruccolo | Ronald Troutman | Agent Peyton Ritter | 1 | 1 |
| Scott Paulin | Navy Capt. Kevin Dorn | Jeffrey Conlon | 1 | 1 |
| Stephen Snedden | Jim Murphy | James "Jimmy" Bond | 1 | 1 |
| Steve Eastin | Frank Smith | Sheriff Mazeroski | 1 | 1 |
| Stuart Margolin | Felix Betts | Dr. They | 1 | 1 |
| Tara Buck | P.O. Tara Marshall | Blueberry | 1 | 1 |
| Tom Bower | Sheriff Miller Thompson | Sheriff Harden | 1 | 1 |
| Tom Gallop | Victor Sterling | Win Shroeder | 1 | 1 |
| Wade Williams | Larry Purcell | Raymond Pearce | 1 | 1 |
| Winston Story | Manny | Bellboy | 1 | 1 |
| Joe Sabatino | HRT Leader Horowitz | Captain Al Triguero | 2 | 1 |
| Lawrence Pressman | Dr. Russell Pike, Secret Service Director | Mr. Milsap | 2 | 1 |
| Wyatt Smith | Frankie | Baby William | 2 | 1 |
| Warren Sweeney | Priest | Dr. Harriman | 1 | 3 |
| Andi Chapman | Congresswoman Bernice Donaldson | Dr. Monique Sackheim | 1 | 1 |
| Brian Leckner | Ben | Hayes Michel | 1 | 1 |
| Caryn West | DCS Department Head Karen Fox | Dr. Libby Nance | 1 | 1 |
| Channon Roe | Sergeant Gordon Lambro | Derek Banks | 1 | 1 |
| Chris Nelson Norris | Retired Marine Captain Chester Kelb | Edmund Peacock, S.W.A.T. Lieutenant | 1 | 2 |
| Coby Ryan McLaughlin | Pete Wilkins | Young Agent #1 | 1 | 1 |
| Cory Blevins | Father | Missionary #1 | 1 | 1 |
| Cyd Strittmatter | Joanne Wright | Dr. Whitney Edwards | 1 | 1 |
| François Chau | Henry Deng | Peter Wong | 1 | 1 |
| Henri Lubatti | Andre Yorka | Dr. Wilkenson | 1 | 1 |
| Holmes Osborne | Fred Hanlan | Mark Johnson | 1 | 1 |
| Javier Grajeda | Dr. Kelly Whelan | Desk Sergeant | 1 | 1 |
| John Billingsley | Jackson Scott | Timothy "Timmy the Geek" Landau | 1 | 1 |
| Kenneth Tigar | Diggar Aldridge | Dr. Plant | 1 | 1 |
| Madison Mason | Marine Lt. Colonel Bushnell | Captain Yip Harburg | 1 | 1 |
| Mandy Levin | Shirley Ives | Ellen Persich | 1 | 1 |
| Randy Oglesby | Army Brigadier General Scott Oliver | Reverend Samuel Mackey | 1 | 1 |
| Rodney Scott | Brian Dempsey | Tony Reed | 1 | 1 |
| Steve Rankin | Sgt. Bill Atlas | U.S. Marshal Daddo | 1 | 1 |
| Steven Flynn | Roman Sobchek | CIA Agent | 1 | 1 |
| John Eric Bentley | Captain Arthur Caldwell | Post Guard | 1 | 2 |
| Judd Trichter | Hunter Huxley | Richie Szalay | 1 | 2 |
| Benito Martinez | Detective Conklin | Orderly | 1 | 1 |
| Bernard White | Afghani Ambassador Qasim Saydia | Dr. Desai | 1 | 1 |
| Brendan Patrick Connor | Travis "Piggy" Phelps | Sheriff Mac Stenzler | 1 | 1 |
| Caroline Lagerfelt | Mrs. Victoria Mallard | Rustic Woman | 1 | 1 |
| Chad Willett | Det. Monteleone | Jim Summers | 1 | 1 |
| Chris Ufland | Gus Zawadzki | Sam | 1 | 1 |
| Darin Cooper | Roy Evans | Deputy Ray Hoese | 1 | 1 |
| David Fabrizio | Marine Col. Frederick Cooper | E.R. Physician | 1 | 1 |
| Hank Harris | Denny Johnson A.K.A Nerdy Man | Dylan Lokensgard | 1 | 1 |
| Jed Rees | Mashir Malik | Lucas Menand | 1 | 1 |
| JoNell Kennedy | Navy Commander Lisa Cleveland | Amina Ngebe | 1 | 1 |
| Katy Boyer | Lieutenant Egan | Dr. Lisa Holland | 1 | 1 |
| Kerrie Keane | Maggie Reed | Nurse | 1 | 1 |
| Kevin McCorkle | Col. Dan McClafferty | Cult Man #2 | 1 | 1 |
| Lou Beatty, Jr. | Issac Curtis | Coach | 1 | 1 |
| Ming Lo | Davey Chen | Dr. Kim | 1 | 1 |
| Mo Gallini | Andre Jones | Hood | 1 | 1 |
| Monnae Michaell | Navy Commander Leandra Womack | Female Coroner | 1 | 1 |
| Morgan Weisser | Vincent Hanlan | Lee Harvey Oswald | 1 | 1 |
| Rodney Eastman | Wendell Kaiser | Ronald Purnell | 1 | 1 |
| Scott MacDonald | Militia Leader | Curtis Delario | 1 | 1 |
| Scott Williamson | Virginia Governor Charles Norin | C.D.C. Leader | 1 | 1 |
| Tyson Turrou | Pete | Blake McCormick | 1 | 1 |
| Aaron D. Spears | Marine Major Michael Strickland | Guard | 1 | 1 |
| Cheryl White | Rebecca Biddle | Nurse #3 | 1 | 1 |
| Conrad Roberts | Benjamin King | Primitive African Man | 1 | 1 |
| Dan Desmond | Grumpy Neighbor | Harry Odell | 1 | 1 |
| Del Zamora | Sergio Morales | Mr. Barreiro | 1 | 1 |
| Erich Anderson | Jack Canton | Doug Underwood | 1 | 1 |
| James Michael Connor | Andrew Pike | Jake Conroy | 1 | 1 |
| James Parks | Brian Sikes | Agent Terry Sullivan | 1 | 1 |
| Lennie Loftin | Frederick Cantor | Coranado | 1 | 1 |
| Lombardo Boyar | Felix Quintero | Deputy Juan Molina | 1 | 1 |
| Michael Wiseman | Chet Tyber | Dr. Rocky Bronzino | 1 | 1 |
| Rick Deats | Navy Admiral John McGee | Dr. Jim Scobie | 1 | 1 |
| Ryan Cutrona | Ray Beringer | Captain | 1 | 1 |
| Scott Alan Smith | Det. Mauceri | Prison Doctor | 1 | 1 |
| Sonny Surowiec | C.K. Cord | Campbell | 1 | 1 |
| Todd Jeffries | Thomas Gardiner | Lead Agent Mayfield | 1 | 1 |
| Tom Virtue | Frank Satner | Dave Kline | 1 | 1 |
| Adam Lieberman | U.S. Customs Officer Cruz | Transit Officer Philbrick | 1 | 1 |
| Ana Maria Lagasca | Maid | Barreiro's Daughter | 1 | 1 |
| Annie O'Donnell | Agnes Anderstout | Elderly Woman | 1 | 1 |
| Ben Reed | Chief P.O. Ian Goetz | Officer | 1 | 1 |
| John O'Brien | Bruce | Missionary #2 | 1 | 1 |
| Jonathan Fraser | Secret Service Officer Jack Lyon | Uniformed Cop | 1 | 1 |
| Karl T. Wright | John Hicks | Associate #1 | 1 | 1 |
| Lee Reherman | Sgt. Tuers | Yuri Volkoff | 1 | 1 |
| Mary-Margaret Lewis | Maude Simmons | Mrs. Dowdy | 1 | 1 |
| Michael Dempsey | Coach Morgan | Sheriff | 1 | 1 |
| Mik Scriba | Mr. Walters | Lieutenant Kraskow | 1 | 1 |
| Robert Joseph | Lt. Commander Folsom | Big Security Guard | 1 | 1 |
| Christian Svensson | Pirate #1 | Soldier #2 | 1 | 1 |
| Edward Diaz | Petty Officer Gomez | El Camino Owner | 1 | 1 |
| Elijah Mahar | Marine Master Sergeant David Marshall | Guard | 1 | 1 |
| Jeff Austin | Colonel Mike Granger | Dr. Nordlinger | 1 | 1 |
| Michael Canavan | Retired Navy Admiral Thomas Garscott | Cameron McPeck | 1 | 1 |
| Phil Abrams | Hotel Manager | Little Fritz | 1 | 1 |
| Philip Lenkowsky | Squeegee Man | Holy Spirit Man #1 | 1 | 1 |
| Ty Upshaw | Security Guard | Officer #1 | 1 | 1 |
| Bo Kane | North Carolina State Trooper William Forman | Marine Sergeant McCormick | 1 | 1 |
| Brian George | Dr. Ameen Temani | Project Doctor | 1 | 1 |
| John Prosky | Carl Dalton | Medical Examiner | 1 | 1 |
| Jordan Marder | Pirate #2 | Creature | 1 | 1 |
| Kevin McClatchy | Lt. David Cameron | James Leeds | 1 | 1 |
| Kim Robillard | Dwayne Parker | Homer | 1 | 1 |
| Rochelle Greenwood | Navy Ensign Cara Blake | Waitress | 1 | 1 |
| Rueben Grundy | Philadelphia P.D. Detective Dubrow | Forensic Tech | 1 | 1 |
| Andy Umberger | FBI Agent Freedman | Agent Chesty Short | 1 | 1 |
| Jeff Bowser | Customer | Redhead Geek | 1 | 1 |
| John Marrott | Master Chief PO RoE | Security Guard | 1 | 1 |
| Maura Soden | Former NCIS Special Agent Melora Koss | Trevor's Mom | 1 | 1 |
| Mary Wickliffe | Nurse Dooley | Nurse | 1 | 1 |
| Wiley Pickett | Navy Captain David Wade | Trooper #2 | 1 | 1 |
Cast data from TVmaze, licensed CC BY-SA 4.0.