Jason Isaacs recently shared that one of his widely recognized co-stars was the “worst bully ever.” Read more here.

With an impressive 176 acting credits over a 37-year span, pinpointing the exact individual is challenging. However, Isaacs mentioned the troubling experience in a 2011 interview with The Telegraph, suggesting the incident occurred before that year.

He shared an anecdote about a star who kept pushing him out of shot during filming, miming entire scenes to sabotage him. In a Monday interview with Vulture, Isaacs added that this unnamed actor “did worse,” engaging in off-camera performances that were entirely different from what was on screen.

“It was awful—something I’d never experienced before,” Isaacs said. “I’d have previously sacrificed anything for this person.”

He declined to name the star, but listed some notable co-stars prior to 2011, including:

• Jeff Goldblum, “The Tall Guy”
• Rowan Atkinson, “The Tall Guy”
• Jude Law, “Shopping”
• Dennis Quaid, “Dragonheart”
• Sean Connery, “Dragonheart”
• Bruce Willis, “Armageddon”
• Billy Bob Thornton, “Armageddon” (1998)
• Ben Affleck, “Armageddon” (1998)
• Owen Wilson, “Armageddon”
• Steve Buscemi, “Armageddon”
• Kurt Russell, “Soldier” & “Grindhouse”
• Mel Gibson, “The Patriot”
• Heath Ledger, “The Patriot”
• Keanu Reeves, “Sweet November”
• Josh Harnett, “Black Hawk Down”
• Nicolas Cage, “Windtalkers”
• Mark Ruffalo, “Windtalkers”
• Jackie Chan, “The Tuxedo”
• Daniel Radcliffe & Ralph Fiennes, “Harry Potter”
• Martin Sheen & Rob Lowe, “The West Wing”
• Danny Trejo, “Tennis, Anyone?” & “Grindhouse”
• John Boyega, “Riding with Sugar”
• Kevin Connolly & Adrian Grenier, “Entourage”
• Jeremy Piven, “Entourage”
• Matt Damon, “Green Zone”
• Taylor Lautner, “Abduction”

Isaacs noted that many of his co-stars have been “bonkers,” though he emphasizes he judges based on behavior. “Bad conduct—selfishness, cruelty, bullying—is what I look out for,” he explained.

He also shared that he witnesses actors skipping work, doing drugs, or calling “prostitutes to their trailer,” though he chooses not to name names, feeling it offers no benefit except to promote sabotage or self-sabotage. “Acting is filled with secrets,” he said.