Dr. Michaela (Mike) Anne Quinn - Jane Seymour
Byron Sully - Joe Lando
Wolf - Cody
Katherine (Katie) Elizabeth Sully - Alexandra, McKenzie and Megan Calabrese
Matthew Cooper - Chad Allen
Ingrid - Jennifer Youngs
Brian Cooper - Shawn Toovey
Colleen Cooper [Cook] - Erika Flores (seasons 1-3); Jessica Bowman (3-6)
Becky Houser (Binder) - Haylie Johnston
Dr. Andrew Cook - Brandon Douglas
Charlotte Cooper - Diane Ladd
Emily Donovan - Heidi Kozak
Missy - Melissa Flores
Loren Bray - Orson Bean
Dorothy Jennings - Barbara Babcock
Cloud Dancing - Larry Sellers
Snow Bird - Tantoo Cardinal
Chief Black Kettle - Nick Ramus
Robert E - Henry G. Sanders
Grace - Jonelle Allen
Anthony - Brenden Jefferson (season 4); Brandon Hammond (season 5 & 6)
Reverend Timothy Johnson - Geoffrey Lower
Hank Lawson - William Shockley
Jake Slicker - Jim Knobeloch
Señora Teresa Morales [Slicker] - Michelle Bonilla (season 4); Alex Meneses (seasons 5-6)
Horace Bing - Frank Collison
Myra [Bing] - Helene Udy
Samantha Bing - Holli Coleman
Emma Morrison - Charlotte Chatton
Alice - Andrea Bakkum
Preston A. Lodge III - Jason Leland Adams (beginning in season 4; played Olive Bray Davis - Gail Strickland
Pup - Cody

***Note:
- James Keach (director) is Jane Seymour's husband.
- Beth Sullivan (producer) is married to Jim Knobeloch (Jake).
- Melissa Flores is Erika's (Colleen) sister.
- Alley Mills (Marjorie Quinn) is married to Orson Bean (Loren Bray).
- Stacey Keach, Sr., Jane Seymour's father-in-law, has appeared in some episodes of Dr. Quinn as a judge.
- Jane Seymour's two children, Katie and Sean, appeared in one episode each of Dr. Quinn
- Jane Seymour and James Keach's twins, Kris and John, and Beth Sullivan and Jim Knobeloch's twins, appeared in Moment of Truth as some of the babies present at Katie's birthday party.
- Katie is played by the Calabrese triplets, Megan, Mackenzie, and Alexandra.

Some additional stars:

Jake Slicker - Colm Meaney (in the Pilot)

Elizabeth Quinn - Georgann Johnson (Jane Wyman in The Visitor)
Marjorie (Quinn) - Alley Mills
Rebecca (Quinn) - Elinor Donahue
[Sheriff] Daniel Simon - John Schneider
- also played a cowboy in Cowboy's Lullaby, season 1
Ethan Cooper - Ben Murphy
Superintendent Hazen - James Sloyan
Jedediah Bancroft - George Furth
Sgt. Terence McKay - David Beecroft
Sgt. O'Connor - Patrick Kilpatrick
Dr. William Burke - Edward Albert
David Lewis/Andrew Strauss - Maxwell Caulfield
Dandy John O'Malley - Steve Blackwood

(For more guest stars, see Episode Guide and the Boarding House)

Major Stars

Barbara Babcock
Chad Allen
Erika Flores
Frank Collison
Gail Strickland
Geoffrey Lower
Helen Udy
Henry G. Sanders
Jane Seymour
Jennifer Youngs
Jessica Bowman
Jim Knobeloch
Joe Lando
Jonelle Allen
Larry Sellers
Orson Bean
Shawn Toovey
William Shockley

Recurring

Alex Meneses
Alexandria Calabrese
Alley Mills
Andrea Bakkum
Brandon Douglas
Brandon Hammond
Brenden Jefferson
Cathy Worthington
Charlotte Chatton
Christopher Keene Kelly
Christopher Kriesa
David Beecroft
Diane Ladd
Edward Albert
Elinor Donahue
Eric Michael Zee
Georgann Johnson
Haylie Johnson
Heidi Kozak
Helene Udy
Jason Leland Adams
Jeff O'Haco
Jerry Hardin
John Schneider
Johnny Cash
Johnny Moran
Mary Rings
McKenzie Calabrese
Megan Calabrese
Melissa Flores
Michelle Bonilla
Nick Ramus
Patrick Kilpatrick
Richard Moll
Tantoo Cardinal
Tim deZarn