Dave Harbour Exits Tony Gilroy’s ‘Behemoth!’ In Mid-Production— Reshoots Needed

UPDATE: Will Arnett (“Is This Thing On?”) has officially replaced Harbour in “Behemoth!” (via Deadline).

EARLIER: I don’t know exactly what’s happening with Dave Harbour, and I’m not in a position to speculate—this is simply a moment to send him my “sincerest well wishes.”

Harbour has exited Tony Gilroy’s “Behemoth!”, with an undisclosed actor stepping in to take over his role. His departure means the scenes he already shot will need to be reshot, adding adjustments to a production that began in late October.

According to multiple sources cited by Variety, Harbour felt “overwhelmed” as “Stranger Things” wrapped and took a break from filming to rest. He has long been candid about his mental health, revealing he was diagnosed with bipolar disorder at 26 following a “particularly intense episode.”

Harbour had already filmed many scenes for “Behemoth!” and, as recently as November, was photographed on set with his co-stars.

Searchlight, which joined the project this summer, was eyeing a fall 2026 release, but Harbour’s exit—and the resulting reshoots—could complicate those plans. The film stars Pedro Pascal, Olivia Wilde, Eva Victor, and—Quentin Tarantino favorite—Matthew Lillard.

Pascal plays a cellist who returns to Los Angeles and begins composing music for films. Told in a nonlinear, music-driven structure, the story uses musical cues to trigger flashbacks spanning the past 20 years, exploring the reasons behind his departure and return.

Gilroy, who made his directorial debut with the critically acclaimed “Michael Clayton” (2007), returns with “Behemoth!” just four years after achieving widespread acclaim for Disney+’s “Andor.”