The Staircase Cast: Who Each Actor Is Playing In The HBO Max Miniseries

Colin Firth and Toni Collette in The Staircase
(Image credit: HBO Max)

The world cannot seem to get enough of true crime - be it a feature-length drama, a series, a documentary, or a docuseries to get every last detail out of the case of the week. It also appears that some stories are more obsessed over than others, such as that of Michael Peterson, whose long-debated case involving of his wife, Kathleen - who was found dead at the bottom of a staircase in 2001 - has been the subject of a feature-length Lifetime movie, a docuseries on Netflix, and now an eight-episode HBO Max original drama called The Staircase.

Whatever your opinion is regarding the shocking trial, I think few can argue that creator Antonio Campos’ miniseries - available to stream on HBO Max Thursday, May 5 - doesn't look like a gripping representation of the events that took place. See for yourself by taking a look at who is playing whom in The Staircase cast.

Colin Firth in The Staircase

(Image credit: HBO Max)

Colin Firth (Michael Peterson)

Playing novelist Michael Peterson - convicted of murder in 2003 before charges were reduced to manslaughter in 2017 - is Colin Firth, whose last true crime title was 2013’s Devil’s Knot. The British actor is better known for literary costume dramas like 1995’s Pride and Prejudice miniseries, biopics like The King’s Speech (for which he won an Oscar), rom-coms like Bridget Jones’ Diary, musicals (namely when he joined the Mamma Mia! cast), or even cartoonish spy thrillers like the action-packed Kingsman movies

Firth more recently played Stanley Tucci’s partner in Supernova, a British Naval officer in 2022’s Operation Mincemeat, and (speaking of war dramas) will reunite with 1917 director Sam Mendes for Empire of Light.

Toni Collette in The Staircase

(Image credit: HBO Max)

Toni Collette (Kathleen Peterson)

Playing Kathleen Peterson - whose mysterious death is the main focus of the story - is Toni Collette, whose previous experience with true crime includes Netflix’s Unbelievable and Imperium. The Australian actress’ eclectic filmography ranges from horror movies like The Sixth Sense (for which she received an Oscar nomination) and Hereditary (for which she should have received an Oscar nomination), to dysfunctional family dramedies like Little Miss Sunshine, the Showtime series United States of Tara (which earned her an Emmy), or more fun mystery thrillers like Knives Out. Collette recently starred in Netflix’s I’m Thinking of Ending Things in 2020 and Guillermo del Toro’s Best Picture Oscar nominee, Nightmare Alley, the following year.  

Michael Stuhlbarg in The Staircase

(Image credit: HBO Max)

Michael Stuhlbarg (David Rudolf)

As Michael Peterson’s lawyer, David Rudolf, we have Michael Stuhlbarg, who (in addition to recently starring on another legal drama, Showtime’s Your Honor) has played a lot real people in fact-based titles. He joined Hulu’s Dopesick cast as former Purdue Pharma president Richard Sackler, gave an Emmy-nominated performance as national security expert Richard Clarke on The Looming Tower, was crime boss Andrew Rothstein on Boardwalk Empire, and sparred with Michael Fassbender in the title role of Steve Jobs as software engineer Andy Hertzfeld, to name just a few. 

He also led Joel and Ethan Coen’s A Serious Man in 2010, played an alien in Men in Black 3, played a human afraid of aliens in Arrival, and is reprising his Doctor Strange role in its sequel in 2022.

Parker Posey in The Staircase

(Image credit: HBO Max)

Parker Posey (Freda Black)

As Freda Black - the prosecuting attorney in the Michael Peterson case - we have Parker Posey, who first broke into the mainstream (like many of her co-stars in the 1993 classic) as Darla in Dazed and Confused, before becoming a recurring cast member of Christopher Guest and Eugene Levy's mockumentaries after first appearing in 1996’s Waiting for Guffman

She is also known for classic rom-coms like You’ve Got Mail, horror movies like Scream 3, and comic book movies like Blade: Trinity and Superman Returns. Posey has also had recurring roles on many notable series (such as The Good Wife), starred on Netflix’s Lost in Space reboot, and will appear in AMC’s upcoming anthology Tales from the Walking Dead.

Dane DeHaan in The Staircase

(Image credit: HBO Max)

Dane DeHaan (Clayton Peterson)

Playing Michael Peterson’s son, Clayton, is Dane DeHaan, who has a few credits in common with his The Staircase co-stars - namely Devil’s Knot with Colin Firth and Lincoln with Michael Stuhlbarg. He is even better known as Andrew Detmer in the acclaimed 2012 found footage thriller Chronicle, Harry Osborn in The Amazing Spider-Man 2, Lockhart in A Cure for Wellness, and the title character of Valerian and the City of a Thousand Planets

Other notable miniseries credits for DeHaan (who recently joined Christopher Nolan’s Oppenheimer cast) include the suspenseful The Stranger (formerly a Quibi exclusive) and Apple TV+’s adaptation of Stephen King’s Lisey’s Story.

Patrick Schwarzenegger in The Staircase

(Image credit: HBO Max)

Patrick Schwarzenegger (Todd Peterson)

Playing Michael Peterson’s son, Todd, is Arnold Schwarzenegger’s son, Patrick Schwarzenegger - who made his acing debut in the 2006 comedy, The Benchwarmers, before reuniting with David Spade and Rob Schneider in 2013’s Grown Ups 2. Before playing the title role of 2019’s Shudder exclusive movie, Daniel Isn’t Real, his first horror efforts were Scouts Guide to the Zombie Apocalypse and an episode of Scream Queens in 2015 and, in the years in between, he played a soldier on National Geographic’s The Long Road Home and shared a romance with Bella Thorne in Midnight Sun (not to be confused with the Twilight spin-off book). 

Schwarzenegger has since shared the screen with Michael Shannon in Echo Boomers, Amy Poehler in Netflix’s Moxie, and Thomas Jane and more in the dystopian ensemble drama, Warning

Sophie Turner in The Staircase

(Image credit: HBO Max)

Sophie Turner (Margaret Ratliff)

Playing Michael Peterson’s adoptive daughter, Margaret Ratliff, is Sophie Turner, although she goes by the last name Jonas since her marriage to Joe Jonas in 2019. Like some of her fellow The Staircase cast members, the English actress has starred in comedic spy movies (2015’s Barely Lethal), Marvel movies (as the X-Men’s Jean Grey), and Quibi original thrillers (Survive from 2020). Of course, Turner (who more recently leant her voice to HBO Max’s animated comedy, The Prince) is best known for her Emmy-nominated performance in the Game of Thrones cast as Sansa Stark. 

Odessa Young in The Staircase

(Image credit: HBO Max)

Odessa Young (Martha Ratliff)

Playing Michael Peterson’s adoptive daughter, Martha Ratliff, is Odessa Young, who previously worked with Colin Firth in 2022’s Mothering Sunday and Michael Stuhlbarg in Shirley two years earlier. Following her starring roles on the Australian dramas Tricky Business (also starring The Boys cast member Antony Starr) and Wonderland, the actress made her feature-length debut in 2015’s The Daughter and later starred in A Million Little Pieces and played the lead of Sam Levinson’s coming-of-age satire, Assassination Nation, in 2018. In 2020, she joined Paramount+’s The Stand cast.

Olivia DeJonge in The Staircase

(Image credit: HBO Max)

Olivia DeJonge (Caitlin Atwater)

As Caitlin Atwater - Kathleen Peterson’s daughter from a previous marriage - we have Olivia DeJonge, who, like some of her fellow The Staircase cast members, has starred in found footage thrillers and worked with M. Night Shyamalan (2015’s The Visit), in Shakespearean costume dramas (TNT’s short-lived series, Will), and dystopian supernatural TV shows (Netflix’s The Society). The Australian actress made her feature-length debut in 2014’s teen mystery The Sisterhood of Night, later starred in the 2016 holiday horror movie Better Watch Out, and will soon appear in Baz Luhrmann’s Elvis as Priscilla Presley.

Rosemarie DeWitt in The Staircase

(Image credit: HBO Max)

Rosemarie DeWitt (Candace Zamperini)

As Candace Zamperini - Kathleen Peterson’s sister - we have Rosemarie DeWitt, who last played Toni Collette’s onscreen sister on the aforementioned United States of Tara. Also like some of her fellow The Staircase cast members, she has starred in dysfunctional family stories (Rachel Getting Married and Your Sister’s Sister), period TV shows (a recurring role in the Mad Men cast), horror movies (2015’s Poltergeist remake), musicals (La La Land), and modern satirical dramas (Men, Women & Children). DeWitt also tried dystopian sci-fi with one of the best Black Mirror episodes from Season 4 (“Arkangel”) and was part of Hulu’s Little Fires Everywhere cast in 2020.

Tim Guinee in The Staircase

(Image credit: HBO Max)

Tim Guinee (Bill Peterson)

Playing Michael Peterson’s brother, Bill, is Tim Guinee, whose last role on a fact-based miniseries this year was on Netflix’s Inventing Anna, after previously starring in the 2019 biopic Harriet, and playing John Denver in the 2002 TV movie Warning: Parental Advisory. His lengthy, versatile filmography also includes vampire movies (John Carpenter’s Vampires and 1998’s Blade - also his first Marvel movie before appearing in the first two Iron Man movies), and a couple other appearances alongside Rosemarie DeWitt (The Odd Life of Timothy Green and Promised Land). He also has recurring roles on several hit series - such as The Good Wife, Hell on Wheels, Elementary, and Homeland

Vincent Vermignon in The Staircase

(Image credit: HBO Max)

Vincent Vermignon (Jean-Xavier de Lestrade)

As Jean-Xavier de Lestrade - the Oscar-winning documentarian behind the docuseries also called The Staircase - we have Vincent Vermignon. Originally from the French-Caribbean island of Martinique, the actor is best known for the 2016 drama Gangs of the Caribbean, the interactive series Cut, and lending his voice to the spooky animated French film Little Vampire in 2020. English-speaking audiences may also recognize the actor from an episode of the Idris Elba-led crime series, Luther, in 2019.

Juliette Binoche in The Staircase

(Image credit: HBO Max)

Juliette Binoche (Sophie Brunet)

Playing Sophie Brunet - Jean-Xavier de Lestrade’s editor who become romantically involved with Michael Peterson during the making of The Staircase docuseries - is Juliette Binoche, who last starred opposite Colin Firth in the Best Picture Oscar winner The English Patient, for which she also won an Academy Award. Like Firth, the French actress is also known for literary romance dramas (1992’s Wuthering Heights), rom-coms (2007’s Dan in Real Life), and big budget blockbusters (2014’s Godzilla), to name a few. The Chocolat star is also known for Michael Haneke’s thriller, Caché, the romantic anthology Paris, je t’aime, and two unique thrillers opposite Robert Pattinson (2012’s Cosmopolis and High Life from 2018).

Murder. Mystery. Romance. Family drama. A talented cast. What more could you ask for from a true crime series like The Staircase on HBO Max?

Jason Wiese
Content Writer

Jason has been writing since he was able to pick up a washable marker, with which he wrote his debut illustrated children's story, later transitioning to a short-lived comic book series and (very) amateur filmmaking before finally settling on pursuing a career in writing about movies in lieu of making them. Look for his name in just about any article related to Batman.