The Staircase (TV) Cast
The cast of The Staircase. Updated on September 18, 2025.
64 actors
Colin Firth
as Michael Peterson (8 episodes)

Colin Firth portrays the lead character, Michael Peterson. Michael is a novelist and former mayoral candidate who finds himself at the center of a murder investigation when his wife is found dead at the bottom of the staircase.

Toni Collette
as Kathleen Peterson (8 episodes)

Toni Collette plays Kathleen Peterson, Michael's wife. Kathleen is a successful business executive, and her tragic death sets off a chain of events that form the basis of the show's gripping story.

Michael Stuhlbarg
as David Rudolf (8 episodes)

Michael Stuhlbarg portrays David Rudolf, Michael Peterson's defense attorney. David is a skilled and dedicated lawyer, determined to prove his client's innocence amidst a web of evidence and suspicion.

Dane DeHaan
as Clayton Peterson (8 episodes)

Dane DeHaan plays Clayton Peterson, Michael's son from a previous marriage. Clayton struggles with the accusations against his father and grapples with the impact it has on his own life and relationships.

Olivia DeJonge
as Caitlin Atwater (8 episodes)

Olivia DeJonge portrays Caitlin Atwater, a journalist assigned to cover the case. Caitlin becomes immersed in the Peterson family's story and uncovers new information that could change the course of the trial.

Patrick Schwarzenegger
as Todd Peterson (8 episodes)

Patrick Schwarzenegger plays Todd Peterson, Michael's biological son. Todd supports his father throughout the trial and stands by him, despite the mounting evidence against him.

Sophie Turner
as Margaret Ratliff (8 episodes)

Sophie Turner portrays Margaret Ratliff, Michael Peterson's adopted daughter. Margaret becomes a key figure in the investigation and provides crucial insight into her family dynamics.

Odessa Young
as Martha Ratliff (8 episodes)

Odessa Young plays Martha Ratliff, Margaret's biological sister and Michael Peterson's other adopted daughter. Martha's perspective and possible involvement in the case add further complexity to the story.

Rosemarie DeWitt
as Candace Zamperini (8 episodes)
Tim Guinee
as Bill Peterson (8 episodes)
Vincent Vermignon
as Jean-Xavier de Lestrade (8 episodes)
Parker Posey
as Freda Black (8 episodes)
Juliette Binoche
as Sophie Brunet (8 episodes)
Giovanni Pucci
as (8 episodes)
Josh Drennen
as Francis Borden (1 episode)
Olek Krupa
as Werner Spitz (1 episode)
Joel McKinnon Miller
as Larry Pollard (4 episodes)
Maria Dizzia
as Lori Campbell (6 episodes)
Susan Pourfar
as Deborah Radisch (5 episodes)
Justice Leak
as Tom Maher (6 episodes)
Cullen Moss
as Jim Hardin (5 episodes)
Cory Scott Allen
as Art Holland (6 episodes)
Jason Davis
as Fred Atwater (4 episodes)
Trini Alvarado
as Patty Peterson (5 episodes)
Frank Feys
as Denis Poncet (5 episodes)
Teri Wyble
as Sonya Pfeiffer (4 episodes)
Robert Crayton
as Ron Guerette (6 episodes)
Donny Boaz
as Tyrone Lacour (2 episodes)
Samuel Ray Gates
as Big Ray (2 episodes)
Mike Forbs
as BK (1 episode)
Paul Teal
as Brad Wolgamott (3 episodes)
Nick McCallum
as James the Masseur (1 episode)
William Ngo
as Make-Up Artist (1 episode)
Hannah Pniewski
as Becky (2 episodes)
Myke Holmes
as Duane Deaver (2 episodes)
Kevin Sizemore
as Mark Zamperini (2 episodes)
Ryan Lewis
as Bruce Campbell (2 episodes)
Kate Sanford
as Veronica Hunt (2 episodes)
Daniela Lee
as Devon (2 episodes)
Andre Martin
as Yves (1 episode)
Deena Wade
as Margaret Blair (1 episode)
Wilky Lau
as Henry Lee (1 episode)
Vince Pisani
as Tim Palmbach (1 episode)
Matthew Jayson Cwern
as Faris Bandak (1 episode)
Morgan Renard
as Dennis Rowe (1 episode)
Scott Johnson
as Jay Trehy (1 episode)
Tedd Taskey
as Weight Lifter (1 episode)
Carl Palmer
as Banker at Gym (1 episode)
John Crow
as Joseph (1 episode)
Joel Ray Ishman
as Police Officer (1 episode)
Jean V Alexander
as Marylou Pollard (1 episode)
Katelyn Farrugia
as Christina Tomasetti (1 episode)
Erika Coleman
as Medical Assistant (1 episode)
Jeff Benninghofen
as Chief M.E. John Butts (1 episode)
Craig Pearman
as Kenneth Snell (1 episode)
Cynthia Barrett
as Carol (1 episode)
Christian Bach
as News Reporter (1 episode)
A.K. Benninghofen
as Charlene Rudolf (1 episode)
Charlton Hoag
as Officer (1 episode)
Angela Davis
as Officer (1 episode)
Ronald Godfrey
as Officer (1 episode)
Viviana Chavez
as Paramedic (1 episode)
Larry Herring
as Paramedic (1 episode)
Dustin Lewis
as Assistant District Attorney (1 episode)
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