All Her Fault Cast and Character Guide

Nivedita Dubey
November 14, 2025

Key Points:

All Her Fault cast features an acclaimed ensemble led by Sarah Snook, Dakota Fanning, and Jake Lacy.
The series adapts Andrea Mara’s bestselling novel into a tense suburban mystery.
Each actor brings depth to characters navigating motherhood, secrets, and suspicion.

All Her Fault has quickly become one of 2025’s most talked-about thrillers, thanks in large part to its exceptional cast. The Peacock series brings Andrea Mara’s bestselling novel to life with layered performances, sharp character work, and a grounded look at modern motherhood under pressure. Set in suburban Chicago, the story follows a missing child case that exposes fractures in a tightly woven community — and the actors behind it elevate every twist.

Who Are the Main All Her Fault Cast Members and What Roles Do They Play?

All Her Fault _ Official Trailer _ Peacock Original — Sarah Snook as Marissa Irvine in All Her Fault cast _ Official Trailer _ Peacock Original

The cast of All Her Fault is packed with award-winning performers who bring nuance to a story rooted in fear, trust, and parental judgment. Here’s a look at the principal actors and the characters they portray.

Sarah Snook as Marissa Irvine

Fresh off her Emmy-winning run as Shiv Roy in Succession, Sarah Snook plays Marissa Irvine, a self-made wealth manager balancing ambition and motherhood. On the surface, Marissa seems fully in control — expertly managing clients, her marriage to commodities trader Peter, and raising five-year-old Milo. But that balance shatters when she arrives to pick up her son from a playdate and finds a stranger at the door.

Snook plays Marissa with a compelling mix of resilience and exhaustion. Her performance captures the pressure working mothers face and the internal math behind every parental decision.

Notable work: Succession, Predestination, Steve Jobs.

Dakota Fanning as Jenny Kaminski

Dakota Fanning portrays Jenny Kaminski, a fellow school parent and head of marketing at Blackhorn. Jenny appears flawless — organized, successful, and composed. But when her nanny becomes the prime suspect in Milo’s disappearance, she faces public scrutiny and personal guilt. Her unexpected friendship with Marissa becomes one of the show’s emotional anchors.

Notable work: I Am Sam, Ripley, Once Upon a Time in Hollywood.

Sophia Lillis as Carrie Finch (Josephine Murphy)

Sophia Lillis takes on one of the show’s most complex roles: Carrie Finch, the nanny with a tightly guarded past. Working under an assumed name, Carrie is later revealed to be Josephine Murphy, a young woman shaped by profound loss. Lillis plays her with unsettling calm, slowly peeling back layers of trauma that ultimately fuel the series’ central mystery.

Notable work: It, Sharp Objects, Nancy Drew and the Hidden Staircase.

Abby Elliott as Lia Irvine in All Her Fault Cast _ Official Trailer _ Peacock OriginalAbby Elliott as Lia Irvine

Abby Elliott as Lia Irvine

Abby Elliott portrays Lia, Peter’s sister. As a recovering addict, Lia carries the weight of past mistakes and becomes an easy target for suspicion. Elliott delivers a grounded performance that avoids stereotype, offering a more empathetic look at someone trying to rebuild their life under a cloud of doubt.

Notable work: The Bear, Saturday Night Live.

Jake Lacy as Peter Irvine

Jake Lacy plays Peter Irvine, Marissa’s husband. At first, he presents himself as the stable, supportive partner. But cracks begin to show — in the clipped tone, the controlling behavior, the insistence on perfection at home. When he says “You are mine,” the line lands like a warning. Lacy charts Peter’s shift from polished professional to something more dangerous with unnerving precision.

Notable work: The White Lotus, High Fidelity.

Michael Peña as Detective Alcaras

Michael Peña plays Detective Alcaras, the investigator assigned to Milo’s disappearance. A father to a non-verbal son with developmental disabilities, Alcaras brings lived empathy to the case. He recognizes the subtle patterns that separate distress from guilt and pieces together connections others overlook. Peña’s performance adds a steadying presence amid escalating tension.

Notable work: Narcos: Mexico, Ant-Man, Crash.

Jay Ellis as Colin Dobbs

Jay Ellis plays Colin Dobbs, Marissa’s longtime friend and work colleague. As someone who knows the Irvine family well, Colin becomes entangled in the investigation — and his loyalty is tested as secrets emerge. His role deepens as the story moves toward its explosive finale.

Notable work: Insecure, Top Gun: Maverick.

Daniel Monks as Brian Irvine

Daniel Monks appears as Brian, Peter and Lia’s brother. His role threads through the family’s past and the unresolved tensions that complicate the investigation. While not a central character, Brian adds texture to the Irvine family dynamic.

Duke McCloud as Milo Irvine

Duke McCloud plays Milo, the missing child at the center of the story. Though young, his presence shapes every character’s choices. Milo’s personality — curious, bright, trusting — raises the emotional stakes of the investigation.

Thomas Cocquerel as Richie

Thomas Cocquerel plays Richie, whose relationship to the core group adds another layer of community dynamics, judgment, and suspicion. While his role is smaller, it helps widen the world beyond the Irvine family and school parents.