| Name | Character | Episodes |
|---|---|---|
| Zach Braff | John 'J.D.' Dorian | 181 |
| John C. McGinley | Perry Cox | 181 |
| Donald Faison | Christopher Turk | 181 |
| Ken Jenkins | Bob Kelso | 176 |
| Sarah Chalke | Elliot Reid | 172 |
| Neil Flynn | Janitor | 169 |
| Judy Reyes | Carla Espinosa | 168 |
| Robert Maschio | Todd | 127 |
| Sam Lloyd | Ted Buckland | 94 |
| Aloma Wright | Laverne Roberts | 89 |
| Christa Miller | Jordan Sullivan | 88 |
| Travis Schuldt | Keith | 40 |
| Eliza Coupe | Denise Mahoney | 23 |
| Charles Rahi Chun | Dr. Wen | 21 |
| Elizabeth Banks | Dr. Kim Briggs | 16 |
| Michael Hobert | Lonnie | 15 |
| George Miserlis | Crispin | 15 |
| Dave Franco | Cole Aaronson | 13 |
| Michael Mosley | Drew Suffin | 13 |
| Kerry Bishé | Lucy Bennett | 13 |
| Scott Foley | Sean Kelly | 12 |
| Tara Reid | Danni | 11 |
| Nicky Whelan | Maya | 10 |
| Heather Graham | Dr. Molly Clock | 9 |
| Michael Learned | Mrs. Wilk | 8 |
| Martin Klebba | Randall | 8 |
| Betsy Beutler | Dr. Katie Collins | 8 |
| Tom Cavanagh | Dan Dorian | 7 |
| Bob Clendenin | Dr. Zeltzer | 7 |
| Matthew Moy | Trang | 7 |
| Jay Kenneth Johnson | Dr. Matthews | 7 |
| Kit Pongetti | Lady | 7 |
| Bellamy Young | Dr. Miller | 6 |
| Nicole Sullivan | Jill Tracy | 6 |
| Tyler Poelle | Boon | 6 |
| Sonal Shah | Dr. Sunny Day | 6 |
| Kate Micucci | Stephanie Gooch | 5 |
| Todd Bosley | Howie | 5 |
| Masi Oka | Franklyn | 5 |
| Matt Winston | Jeffrey Steadman | 5 |
| Phill Lewis | Hooch | 5 |
| Chrystee Pharris | Kylie | 5 |
| Amy Smart | Jamie Moyer | 4 |
| Michael Weston | Private Brian Dancer | 4 |
| Donald Sage Mackay | Doctor | 4 |
| Richard Kind | Mr. Corman | 4 |
| Rick Schroder | Paul | 4 |
| Taran Killam | Jimmy | 4 |
| Aziz Ansari | Ed | 4 |
| Josh Randall | Jake | 4 |
| Aseem Batra | Josephine | 4 |
| Michael McDonald | Mike Davis | 4 |
| Shaughn Buchholz | Cabbage | 4 |
| Courteney Cox | Dr. Maddox | 3 |
| Brendan Fraser | Ben Sullivan | 3 |
| Sarah Lancaster | Lisa | 3 |
| Freddy Rodríguez | Mark | 3 |
| Markie Post | Lily Reid | 3 |
| Lee Thompson Young | Derek | 3 |
| Elizabeth Bogush | Alex | 3 |
| Aloma Wright | Nurse Shirley | 3 |
| Jill Tracy | Elaine | 3 |
| Lindsey Stoddart | Lauren | 3 |
| Alexander Chaplin | Mr. Thompson | 3 |
| Kathryn Joosten | Mrs. Tanner | 3 |
| Paige Peterson | Shelly | 3 |
| Michael J. Fox | Kevin Casey | 2 |
| Kelli Williams | Kristen Murphy | 2 |
| Julianna Margulies | Neena | 2 |
| Mandy Moore | Julie | 2 |
| Dave Foley | Dr. Hedrick | 2 |
| Heather Locklear | Julie Keaton | 2 |
| Keri Russell | Melody | 2 |
| Don Perry | Mr. Bober | 2 |
| Fred Stoller | Mr. Hoffner | 2 |
| Jimmie Walker | Jimmie Walker | 2 |
| Hattie Winston | Margaret Turk | 2 |
| Peter Holden | Mr. Macrae | 2 |
| Jack Shearer | Aaron Simon | 2 |
| Arthur Roberts | Board Member | 2 |
| Spice Williams-Crosby | Donna | 2 |
| Colin Hay | Troubador | 2 |
| Keli Daniels | Nurse | 2 |
| Ravi Patel | Intern | 2 |
| Walter Addison | Ben | 2 |
| Stephanie D'Abruzzo | Patti | 2 |
| Shaughn Buchholz | Cabbage / Jason | 2 |
| Shaughn Buchholz | Jason | 2 |
| Debra Azar | Dr. Donna | 2 |
| Angee Hughes | Nurse | 2 |
| Katie O'Rourke | Coffee Nurse | 2 |
| Keeshan Giles | Lester | 2 |
| Monica Allgeier | Nurse Tisdale | 2 |
| Lela Lee | Bonnie | 2 |
| Candice Coke | Maria Espinosa | 2 |
| Tom Schmid | Fellowship Director | 2 |
| Biff Yeager | Dr. Walch | 2 |
| Lane Davies | Simon Reid | 2 |
| Antonio Sabàto, Jr. | Antonio Sabàto Jr. | 2 |
| Sam Jaeger | Steve Larkin | 1 |
| Ryan Reynolds | Spence | 1 |
| Gary Busey | Gary Busey | 1 |
| Colin Farrell | Billy | 1 |
| Paul Adelstein | Dr. Stone | 1 |
| Jason Bateman | Mr. Sutton | 1 |
| Embeth Davidtz | Maddie | 1 |
| Verne Troyer | Small Man at Bar | 1 |
| Common | Common | 1 |
| DJ Qualls | Josh | 1 |
| Mary Mouser | Girl | 1 |
| Dick Van Dyke | Dr. Townshend | 1 |
| Maureen McCormick | Maureen McCormick | 1 |
| Alan Ruck | Mr. Bragin | 1 |
| Nestor Carbonell | Dr. Ramirez | 1 |
| Julia Campbell | Mrs. Fremont | 1 |
| Julie Warner | Allison | 1 |
| John Billingsley | Alan | 1 |
| Peter Jacobson | Mr. Foster | 1 |
| William Daniels | Dr. Douglas | 1 |
| Christopher Meloni | Dr. Norris | 1 |
| Torrey DeVitto | Gorgeous Girl | 1 |
| Guilford Adams | Intern | 1 |
| Jim Hanks | Dr. Turner | 1 |
| Josh Hammond | Razor | 1 |
| Tim Haldeman | Mr. Warner | 1 |
| Margaret Easley | J.D.'s Mother | 1 |
| Donald Sage Mackay | Dr. Page | 1 |
| Jerry Kernion | Cotton Candy Man | 1 |
| Rachel Winfree | Jill's Mom | 1 |
| Dayna Devon | Nurse | 1 |
| Cayden Boyd | Hummer | 1 |
| Time Winters | Jesus | 1 |
| Erik Estrada | Erik Estrada | 1 |
| Mircea Monroe | Heather | 1 |
| Molly Shannon | Denise Lemmon | 1 |
| George Takei | George Takei | 1 |
| Cheryl Hines | Paige | 1 |
| Loren Lester | Vet | 1 |
| Jay Leno | Jay Leno | 1 |
| John Ritter | Sam Dorian | 1 |
| Nadine Velazquez | Nicole | 1 |
| Jennifer O'Dell | Stunning Woman | 1 |
| Matthew Perry | Murray | 1 |
| Billy Dee Williams | Billy Dee Williams | 1 |
| Jay Mohr | Dr. Peter Fisher | 1 |
| Glynn Turman | George | 1 |
| Liliana Mumy | Samantha Tanner | 1 |
| Joe Manganiello | Chad | 1 |
| Eric Laneuville | Dr. Lamar | 1 |
| R. Lee Ermey | Janitor's Father | 1 |
| Scott Weinger | Dr. Kershnar | 1 |
| Sarah Ramos | Lindsay | 1 |
| Tim DeKay | Mr. Hill | 1 |
| Reno Wilson | Russell Vaughn | 1 |
| Charles C. Stevenson Jr. | Patient | 1 |
| Bernie Kopell | Mr. Moran | 1 |
| Jack Angel | PA System / Announcer | 1 |
| Eric Bogosian | Dr. Gross | 1 |
| Van Epperson | Mr. Mariani | 1 |
| Barry Williams | Barry Williams | 1 |
| Mindy Sterling | Mrs. Cropper | 1 |
| Gillian Vigman | Female Patient | 1 |
| Kevin Rahm | Mr. Hutnik | 1 |
| Louie Anderson | Louie Anderson | 1 |
| Mike Starr | Mr. Iverson | 1 |
| Andrew Friedman | EMT | 1 |
| Marisa Petroro | Cavewoman | 1 |
| Michael Copon | Pedro | 1 |
| Cheyenne Haynes | Daughter | 1 |
| Lauren Stamile | Shannon | 1 |
| Barry Bostwick | Mr. Randolph | 1 |
| Kareem Abdul-Jabbar | Kareem Abdul-Jabbar | 1 |
| Robert Noble | Chaplain | 1 |
| Jill Basey | Mrs. Kellerman | 1 |
| Kevin Cooney | Mr. Woodbury | 1 |
| Scott Menville | Rabbit (voice) | 1 |
| Juanita Jennings | Dr. Munson | 1 |
| Steven Wash Jr. | Young Turk | 1 |
| John Bennett Perry | Harrison | 1 |
| Paul Dooley | Paul | 1 |
| Jeanette Miller | Betty | 1 |
| Toshi Toda | Mr. Chuang | 1 |
| Sloan Robinson | Cafeteria Worker | 1 |
| Carol Herman | Mrs. Carter | 1 |
| D.L. Hughley | Kevin Turk | 1 |
| Edith Fields | Mrs. Foster | 1 |
| Paul Raci | Drunk Guy | 1 |
| Michael Bunin | Jerry | 1 |
| Ned Bellamy | Dr. Green | 1 |
| Brian Oerly | Angry Neighbor | 1 |
| Marshall Manesh | Pizza Guy | 1 |
| Marshall Manesh | Akbar | 1 |
| Marshall Manesh | Dr. Akbar | 1 |
| Eve Brent | Mrs. Harris | 1 |
| Takayo Fischer | Mrs. Cheng | 1 |
| James Michael Tyler | Therapist | 1 |
| Jack Walsh | Unconscious Patient | 1 |
| Kevin West | Mr. Mehleison | 1 |
| Amy Tolsky | Nurse | 1 |
| Houston Rhines | Brother | 1 |
| Marcy Goldman | Mrs. Watson | 1 |
| Carter Jenkins | Young Todd | 1 |
| Jon Polito | Mr. Summers | 1 |
| Earl Schuman | Patient | 1 |
| Shanola Hampton | Woman | 1 |
| Ed Begley Jr. | Dr. Bailey | 1 |
| Mike Weinberg | Tyler | 1 |
| J.P. Manoux | Charlie | 1 |
| Josh Cooke | Dan | 1 |
| Kevin Clash | Elmo (voice) | 1 |
| David Clennon | Dr. Turner | 1 |
| Judy Kain | Irene Kelly | 1 |
| Julian Acosta | Jesus | 1 |
| Lee Arenberg | Dr. Moyer | 1 |
| Mike Henry | Dr. Henry | 1 |
| Mary Kate Schellhardt | Carol | 1 |
| Dan Ponce | Greaser | 1 |
| Anthony Russell | Mr. Lawton | 1 |
| Stephen Furst | Dr. Franklyn | 1 |
| Traber Burns | Mr. Russell | 1 |
| Elizabeth Bogush | Alex Hanson | 1 |
| Lyn Alicia Henderson | Rebecca | 1 |
| Ed McMahon | Ed McMahon | 1 |
| Dayo Ade | Mr. Hovey | 1 |
| Juan Carlos Cantu | Hector | 1 |
| DaJuan Johnson | Intern | 1 |
| Sean Whalen | Laddy | 1 |
| Christopher Darga | Homeless Steve | 1 |
| Travis Wester | David Morrison | 1 |
| Michael Patrick McGill | Officer Brady | 1 |
| Zach Mills | Young J.D. | 1 |
| William Brent | Devin | 1 |
| Leslie David Baker | Surgery Patient | 1 |
| Bruce Kirby | Mr. Bilbray | 1 |
| George Wallace | Minister | 1 |
| Al Harrington | Older Patient | 1 |
| Cullen Douglas | Two O'Clock Man | 1 |
| Cullen Douglas | Patrick | 1 |
| Duke Stroud | Board Member | 1 |
| Victoria Tennant | Maggie | 1 |
| Allison Smith | Millie | 1 |
| Mary Gillis | Mrs Pratt | 1 |
| Efren Ramirez | Ricky | 1 |
| Edward James Gage | Cop | 1 |
| Jean St. James | Mrs. Powell | 1 |
| Jason-Shane Scott | Mike | 1 |
| Keith Allan | Bartender | 1 |
| Mercy Malick | Contortionist | 1 |
| Jerod Mixon | Herbert | 1 |
| Kerris Dorsey | Kid | 1 |
| Richard Cansino | Dr. Rose | 1 |
| Janet Carroll | Mrs. Cooke | 1 |
| Beans Morocco | Artie | 1 |
| Frank Novak | Pat Rosell | 1 |
| Cheryl White | Miss Himsel | 1 |
| John Balma | Owner | 1 |
| Eric Jacobson | Grover (voice) | 1 |
| Marcus Folmar | Mr. Tillman | 1 |
| Mary-Margaret Lewis | Woman | 1 |
| Dougald Park | Mr. Fitzpatrick | 1 |
| Tacey Adams | Woman | 1 |
| Sean Hayes | Nick | 1 |
| Katherine Disque | Waitress | 1 |
| Maria Menounos | Tamara | 1 |
| Michael McDonald | Dr. Toilet (voice) | 1 |
| Michael McDonald | Mr. Cropper | 1 |
| Scott Rinker | Mr. Halford | 1 |
| Matt Bush | Teenage Boy | 1 |
| Trevor Wright | Kid | 1 |
| Bill Lawrence | Justice of the Peace | 1 |
| Bill Lawrence | Cafeteria Client | 1 |
| Bill Lawrence | Janitor | 1 |
| Robert Pierce | Dr. Shapiro | 1 |
| Benjamin King | Milos | 1 |
| Timothy Davis-Reed | Interviewer | 1 |
| Ingo Neuhaus | Hermann Mueller | 1 |
| Carlos Jacott | Dr. No-Shot | 1 |
| Jack Axelrod | Italian Man | 1 |
| David Pressman | Mickey | 1 |
| Ken Lerner | Mr. James | 1 |
| Portia Dawson | Mrs. Bell | 1 |
| Jeremy Howard | Fat Frank | 1 |
| Colin Hay | Colin Hay | 1 |
| Joe Souza | Guy | 1 |
| Katie Gill | Marian | 1 |
| Wes Robinson | Jake | 1 |
| Bob Rumnock | Patient | 1 |
| Cole Williams | Mike | 1 |
| Michael Cotter | Intern | 1 |
| Michael Cotter | Michael | 1 |
| Michael Cotter | Doctor | 1 |
| Michael Cotter | Resident | 1 |
| Troy Kotsur | Mr. Frances | 1 |
| Michael Spiller | The Balloon Guy | 1 |
| Andre B. Blake | Paramedic | 1 |
| Stephon Fuller | Salesman | 1 |
| Fred Berry | Fred Berry | 1 |
| Chuck Woolery | Chuck Woolery | 1 |
| Beverly Polcyn | Dyslexic Woman | 1 |
| Paul Hipp | Marc | 1 |
| Jordi Caballero | Massimo | 1 |
| Don Chastain | Mr. Chambers | 1 |
| Michael Alaimo | Mr. Radford | 1 |
| Carole Davis | Rosie | 1 |
| David Cade | Boots | 1 |
| John Ducey | Will Forte | 1 |
| Ron Ostrow | Mr. Foster | 1 |
| Michael McMillian | Patrick | 1 |
| Jack Yang | Patient | 1 |
| Tate Hanyok | Debbie | 1 |
| Joe Sabatino | Cop | 1 |
| William Bassett | Patient | 1 |
| Myra Turley | Woman | 1 |
| Brian McGovern | Dr. DiStefano | 1 |
| Ed Brigadier | Barber | 1 |
| Linda Porter | Old Woman | 1 |
| Larry Sullivan | Eric Coleman | 1 |
| Clay Aiken | Kenny | 1 |
| Lewis Dauber | Mr. Vaughn | 1 |
| Hira Ambrosino | Realtor | 1 |
| Gina DeVivo | Stephanie | 1 |
| Jessica Kate Meyer | Stephanie | 1 |
| Gina Morelli | Carla's Mom | 1 |
| Caroll Spinney | Oscar the Grouch (voice) | 1 |
| Paul Collins | Dr. Benson | 1 |
| Stacy Barnhisel | Mrs. Marrick | 1 |
| Gary Kraus | Salesman | 1 |
| Phyllis Applegate | Mrs. Kaye | 1 |
| Phoebe Dorin | Mrs. Jensen | 1 |
| Sean Carrigan | Paul | 1 |
| Evelina Turen | Blonde | 1 |
| Helen Geller | Mrs. Fishman | 1 |
| Timothy Starks | Man | 1 |
| Darlene Kardon | Patient | 1 |
| Susan Grace | Woman | 1 |
| Christopher Gehrman | Mr. Candy | 1 |
| Sybil Azur | Mother | 1 |
| Jennie Ventriss | Pat | 1 |
| David Goryl | Mr. Fremont | 1 |
| Shelley Malil | Bartender | 1 |
| D. Elliot Woods | Security Guard | 1 |
| Lindsey Stoddart | Nurse Haltson | 1 |
| Carrot Top | Carrot Top | 1 |
| Larkin Campbell | Maintenance Man | 1 |
| Larkin Campbell | Guy | 1 |
| Troy Bishop | College Dude | 1 |
| Robert Munns | Mr. Kavanaugh | 1 |
| Ric Sarabia | S&M Guy | 1 |
| David Weidoff | Intern | 1 |
| Chris Hogan | Mr. Gerst | 1 |
| Ross Mackenzie | Patient | 1 |
| Ross Mackenzie | Man | 1 |
| Janelle Marra | Sheila | 1 |
| Janelle Marra | Nurse | 1 |
| Marcia Ann Burrs | Peggy | 1 |
| Marjorie Lovett | Mrs. Sheldon | 1 |
| Kelli Kirkland | Rochelle | 1 |
| Cooper Thornton | Tommy Tanner | 1 |
| Stephanie D'Abruzzo | A.M. Muppet (Ex Ray) (voice) | 1 |
| Joe Costanza | Mr. Kellerman | 1 |
| Rich Piana | Monster | 1 |
| Adam Zolotin | Reuben | 1 |
| Benton Jennings | Mr. Hobbs | 1 |
| Herman Poppe | Mr. Porter | 1 |
| Cecelia Antoinette | Mrs. Duncan | 1 |
| Andy Pessoa | Bobby | 1 |
| Matt Kaminsky | Mr. Milligan | 1 |
| Irene White | Janice | 1 |
| Michael Hobert | Pizza Guy | 1 |
| Patrick Macmanus | Frat Boy | 1 |
| Monica Allison | Attractive Woman | 1 |
| Susan Bjurman | Woman | 1 |
| Jan Devereaux | Female Resident | 1 |
| Sonal Shah | Sunny Day | 1 |
| Daniel Edward Mora | Father | 1 |
| Warren Munson | Mr. Taylor | 1 |
| Michael Mitchell | Emery | 1 |
| Monica Garcia Pérez | Sperm Bank Nurse | 1 |
| Al Checco | Man in Bed | 1 |
| Annie Little | Christine | 1 |
| Ralph Cole Jr. | Glen | 1 |
| Adam Harrington | Jack Moyer | 1 |
| Dan Sachoff | Matthew | 1 |
| Dan Sachoff | Professor | 1 |
| Bill J. Stevens | Board Member | 1 |
| James Ritz | Mr. Hicks | 1 |
| Natalie Farrey | Employee | 1 |
| Natalie Farrey | Daisy | 1 |
| Larry Udy | Mr. Grimmett | 1 |
| Larry Udy | Mr. Weisfelner | 1 |
| John O'Brien | Man | 1 |
| Betty A. Bridges | Ms. Simmons | 1 |
| Paul Kwo | Potions Tech | 1 |
| Kit Pongetti | Dr. Mitchell | 1 |
| Kaidy Kuna | Father | 1 |
| Harriett S. Miller | Elderly Woman | 1 |
| Daniel Graves | Older Buisnessman | 1 |
| Fred Ornstein | Bus Driver | 1 |
| Rachel Avery | Jenny | 1 |
| Rachel Avery | Katie | 1 |
| Chad Broskey | Rod | 1 |
| Shannon Welles | Old Woman | 1 |
| Meredith Bishop | Melissa | 1 |
| Andy Forrest | Teacher | 1 |
| David Copperfield | David Copperfield | 1 |
| Matthew J. Evans | Kid | 1 |
| Nancy Daly | Mrs. Gallin | 1 |
| Jennifer Lothrop | Girl | 1 |
| Richard Augustine | Inmate | 1 |
| Terrence Beasor | Man in Bed | 1 |
| Kareem Ferguson | Waiter | 1 |
| Gregory Hinton | Bouncer | 1 |
| Weston Nathanson | Old Man | 1 |
| Oleg Zatsepin | Mover | 1 |
| Sara Van Horn | Mrs. Emmett | 1 |
| Barry Kivel | Mr. Hilliard | 1 |
| Jennifer Leigh Warren | Patient | 1 |
| Peter A. Hulne | Frank | 1 |
| Susan Leslie | Mrs. Winston | 1 |
| Peter Choi | Sushi Chef | 1 |
| Noel Arthur | Frat Guy | 1 |
| Garrett Donovan | Baby Marrick | 1 |
| Garrett Donovan | Councilman Donovan | 1 |
| Bronwen Booth | Anchorwoman | 1 |
| Bronwen Booth | Miss Myers | 1 |
| Soren Hellerup | Rolf Mueller | 1 |
| Barry Cutler | Brett | 1 |
| Tom Ormeny | Arthur | 1 |
| Nathan Lee Graham | Eric / Devin | 1 |
| Adrian Armas | Handsome Man | 1 |
| Larry Thomas | Larry | 1 |
| Jennifer Jostyn | Dr. Simmons | 1 |
| Stacey Hinnen | Mr. Morgan | 1 |
| Gail Borges | Woman | 1 |
| Henry LeBlanc | Eric McNair | 1 |
| Rick Irwin | Dr. Mahoney | 1 |
| Marcus Ashley | ER Doctor | 1 |
| Bonnie Perlman | Mrs. Farr | 1 |
| Steven Cragg | Lt. Underhill | 1 |
| Ellerine Harding | Old Woman | 1 |
| Kellie Madison | Girl | 1 |
| Maurice Warfield | Laverne's Uncle | 1 |
| Robert Dolan | Mr. Winston | 1 |
| Susan Bolles | Mrs. Zeltzer | 1 |
| Alisha Gaddis | Nurses Aide (uncredited) | 1 |
| Jordan Feldman | Scott Gerber | 1 |
| Rochelle Robinson | Woman | 1 |
| Michael Edwin | Mr. Bell | 1 |
| James Henriksen | Husband | 1 |
| Michael Boatman | Ron | 1 |
| Lela Lee | Surgical Intern | 1 |
| Ellen Albertini Dow | Betty | 1 |
| Bonita Friedericy | Nurse | 1 |
| Greg Allan Martin | Tan Doctor | 1 |
| Jonathan Conrad | Justin | 1 |
| Vanessa Marshall | Becky | 1 |
| Timmy Deters | Boy | 1 |
| Sterling Beaumon | Josh | 1 |
| David Warshofsky | Dave Bradford | 1 |
| Paige Peterson | Surgical Nurse | 1 |
| Adrian N. Roberts | Security Guard | 1 |
| Alpheus Merchant | Sleeping Patient | 1 |
| Mary Kathleen Gordon | Mrs. Cole | 1 |
| Sam Menning | Mr. Booker | 1 |
| Zaid Farid | Mr. Strauss | 1 |
| J.B. Ghuman Jr. | Mark | 1 |
| Boris Kievsky | Elliot Man | 1 |
| Linda Tomassone | Paige | 1 |
| Susanne Blakeslee | Gayle | 1 |
| Cathleen Kaelyn | Mrs. Halford | 1 |
| Jeffrey Hutchinson | Dr. Berman | 1 |