Peter Cullen, the veteran voice actor whose deep, commanding delivery gave life to Optimus Prime — the noble leader of the Autobots in the long-running Transformers franchise — has died at the age of 85. Cullen passed away on Wednesday at his home in Los Angeles. No cause of death was announced.

Cullen's career in animation stretched across decades and an extraordinary range of beloved characters. During the 1980s, he voiced American versions of the Smurfs, the Gummi Bears, My Little Pony, G.I. Joe, and the Snorks, among others. He had found his way into the industry through announcing work and acting on variety television before animation became his primary calling. He also made memorable forays into live-action film, providing the roars of King Kong in the 1976 remake and the chilling clicking sounds of the Predator in the 1987 Arnold Schwarzenegger thriller. He additionally lent his voice to Eeyore, the perpetually gloomy donkey in Disney's Winnie the Pooh cartoons.

But it was Optimus Prime — the benevolent Autobot commander from the planet Cybertron who protects Earth against the treacherous Decepticons — that became his defining creation. When Cullen auditioned for the role in 1984, he drew on an unconventional source of inspiration: his older brother Larry, a Marine who had served in the Vietnam War. "He was my hero, he was absolutely a major influence on the character," Cullen said in interviews. "I just imitated him, and through that he lives on for me after his death — every time I do Prime, my brother Larry is there too." The sonorous voice he crafted was designed to convey integrity, dignity, compassion, and authority. Cullen returned to the role across the original animated television series and toy line, subsequent animated films, and the blockbuster live-action film series directed by Michael Bay.

Cullen took evident joy in the multigenerational loyalty his work inspired. At fan conventions, he frequently encountered fathers moved to tears by hearing Optimus Prime's voice — a reaction that, he noted with warmth, baffled their children. Why this matters: Cullen's career is a reminder of the profound, often underappreciated craft of voice acting. His portrayal of Optimus Prime shaped a heroic archetype that resonated with audiences across more than four decades, and his passing marks the end of an era for generations of fans worldwide.