William Shatner, Mia Farrow and More Hollywood Stars Pay Tribute to Brian Dennehy

The Tony-winning actor, who died Wednesday of natural causes at the age of 81, was known for such roles as basketball coach Bobby Knight, Chicago cop Jack Reed and serial killer John Wayne Gacy.

Brian Dennehy, the Tony-winning actor who made an indelible mark on the entertainment industry with memorable work in film, television and theater, died Wednesday of natural causes. He was 81.

In the wake of his death, Hollywood figures have taken to social media to pay tribute to the actor, who was known for such roles as basketball coach Bobby Knight, Chicago cop Jack Reed and serial killer John Wayne Gacy.

William Shatner was one of the first to react to the news, writing on Twitter, "Condolonces to the family of Brian Dennehy. A wonderfully talented actor."

Meanwhile, Mia Farrow tweeted a sweet message accompanied by a photo of Dennehy holding her dog Bowie. "Just devastated to learn that the magnificent Brian Dennehy has died. They is no one i enjoyed working with more," she wrote. "And there are few friends as valued in my life. I took this photo backstage when we were in Love Letters. He loved my pup Bowie."

Laverne & Shirley star Michael McKean called Dennehy "brilliant and versatile," adding that he was "a powerhouse actor and a very nice man as well."

"I met Brian in a bar, acted in a movie with him but the stage is what he loved," Emmy-winning actress Dana Delany wrote. "In rehearsal, he said, 'This is it, kid.' He was a fellow nutmegger, mick and a Marine. They don't make this kind anymore. [Love] to his family."

Oscar winner Marlee Matlin tweeted, "He was a truly tremendous actor and his passing is such a terrible loss. Sending condolences to his daughter Elizabeth and the entire family. RIP."

See more reactions to Dennehy's death below.