Peter Cullen, the voice actor whose baritone defined Optimus Prime across four decades of Transformers cartoons and films, died Thursday, Aug. 27, at his Los Angeles home. He was 85.

His agent, Kevin Motley, confirmed the death to the Los Angeles Times. No cause of death was given.

Cullen's family said he passed away peacefully, surrounded by loved ones. They asked fans to honor his legacy through community service and leadership guided by compassion, integrity and loyalty.

Born July 28, 1941, in Montreal to American parents, Cullen graduated from the National Theatre School of Canada in 1963. He performed Shakespeare in Stratford, Ontario, and spent a year with the repertory company at Toronto's Crest Theatre before moving to television. He appeared on "The Sonny & Cher Show" and "The Smothers Brothers Comedy Hour" before turning to voice work full time.

The role that made him iconic came in 1984, when he first voiced the Autobot leader in the syndicated "Transformers" animated series. Cullen modeled the character on his older brother Larry, a U.S. Marine who served in Vietnam.

"He said, 'Don't go yelling and screaming. He's strong enough to be gentle,'" Cullen recalled of Larry's advice before the audition, according to The Guardian. "When he drops down, when he gets serious, is where I found Optimus Prime."

Cullen gave Larry a cut of his Optimus Prime wages until Larry's death in 2011.

He reprised the role in seven live-action Transformers films between 2007 and 2023, beginning with Michael Bay's blockbuster reboot. The franchise has grossed $5.42 billion worldwide across eight films.

Beyond the Autobot leader, Cullen amassed more than 200 credits. He voiced Eeyore in Disney's Winnie the Pooh projects starting with the 1988 TV series "The New Adventures of Winnie the Pooh." He provided the alien clicking sounds in the 1987 Arnold Schwarzenegger film "Predator," voiced King Kong in the 1976 remake and played the villainous KARR in "Knight Rider."

His animated work stretched across "DuckTales," "Spider-Man," "Chip 'n Dale Rescue Rangers," "My Little Pony," "Dungeons & Dragons" and "Gummi Bears."

Cullen received a Lifetime Achievement Award at the Children's and Family Emmy Awards in 2023. He earned a Daytime Emmy nomination in 2011 for his work as Optimus Prime in "Transformers: Prime."

He was a fixture at fan conventions, where multigenerational crowds lined up to hear that voice in person. Speaking before MegaCon Orlando in 2019, Cullen described the experience: "I expect that I will run into a father with his son, and the father will more than likely get choked up. And then I get choked up, and then the kid is saying 'What are these two grown men getting choked up about?'"

Cullen is survived by his four children: Angus, Claire, Pilar and Clay.