Arabella Olivia Clark stars as Bela in the supernatural horror film Other Mommy, which debuted at No. 1 with a $12.6 million domestic opening day on October 9, 2026. Directed by Rob Savage and produced by James Wan, the Blumhouse and Atomic Monster release pairs the 10-year-old actress with Jessica Chastain and Jay Duplass.
Ten-year-old actress Arabella Olivia Clark stepped into the spotlight following the release of Other Mommy in theaters on October 9. Released on a Friday, the Rob Savage-directed feature film dominated the domestic box office immediately, bringing in $12.6 million domestically on its opening day. In the film, Clark portrays Bela, the young daughter of Ursula, played by Jessica Chastain, and Russ, played by Jay Duplass. The central horror of the narrative revolves around a sinister entity mirroring the mother’s appearance, known as the titular Other Mommy.
Josh Malerman Novel Adaptation and Stunt Work on Set
The supernatural horror film is based on Josh Malerman’s bestselling novel Incidents Around the House. Before landing the role of Bela, Clark prepared extensively by reading the source material in just three days, describing the project as her unicorn of a film role
. Her preparation also extended to demanding physical stunts on set, including acrobatics, flips, and extensive underwater work inside a massive 20-foot-deep pool tank. The production features an ensemble cast that includes Dichen Lachman, Arian Moayed, and Karen Allen alongside the main trio of Clark, Chastain, and Duplass.
“She had that Sherpa hoodie on, pulling her down, and they had the pyrotechnic people where there was an explosion in the water. And they had to yank her underwater. The timing and everything was so well orchestrated. But of course, as a mom, it was very anxiety-producing.”
Rachel Clark, via Yahoo
Despite the intense physical sequences, Clark embraced the challenges. The opportunity allowed the young performer to step directly into the lead of a major horror film alongside an established Hollywood cast. Outside of her work on screen, her adventurous spirit is reflected in taking swimming and sailing lessons, the former of which proved particularly useful for tackling heavy underwater tank stunts during production.
Behind the Scenes With Jessica Chastain and Mckenna Grace
Off-camera downtime during production offered unique learning experiences. Clark spent significant time with co-star Jessica Chastain, observing the actress balance parenting, filming, and studying for Harvard from her trailer. The young actress also shared memories of lighter moments on set, recalling how Chastain would surprise the crew with a loud witch cackle during breaks when the cameras were not rolling.
Clark also established a professional and personal connection with former child actress Mckenna Grace. According to Rachel Clark, Mckenna Grace reached out directly to offer mentorship, establishing an online dialogue to help guide the young performer through the realities of growing up inside the entertainment industry.