By the early 1980s, Cullen was voicing Venger in the animated Dungeons & Dragons series. In 1984, he contributed voices to Gremlins and auditioned for a new animated programme based on Hasbro’s transforming robot toys.
He won the role of Autobot leader Optimus Prime in the original The Transformers series, which ran from 1984 to 1987. His deep, measured performance gave Prime authority without making him cold. The approach came from advice offered by Cullen’s brother, a Marine veteran, who told him that a true hero should be “strong enough to be gentle.”
That idea became the centre of the performance. Prime could command an interplanetary war and still sound concerned about the people caught underneath it, a quality not always guaranteed in stories involving enormous machines punching each other.
Why Optimus Prime kept returning
Cullen’s association with the character lasted 42 years. Even Optimus Prime’s death in 1986’s The Transformers: The Movie could not end it. The decision caused such an outcry among young viewers that the character, and Cullen, returned in 1987. Corporate storytelling had discovered that killing a beloved hero could upset the children buying the merchandise.
When director Michael Bay began developing the first live-action Transformers film, released in 2007, Liam Neeson was reportedly his initial model for Prime. Industrial Light & Magic animators were instructed to use Neeson as a reference for the character’s presence.
According to Bay’s commentary for the film, producers pushed for Cullen to audition and return. He ultimately voiced Optimus Prime throughout Bay’s five films, then continued in Bumblebee and Transformers: Rise of the Beasts. That brought his total to seven live-action appearances, alongside numerous animated series, video games and promotional projects.
Cullen’s performance remained definitive even as the franchise occasionally cast other actors as versions of Prime, including in the 2024 animated film Transformers One. His death leaves Hasbro with a difficult succession question: plenty of performers can produce a commanding low voice, but imitation is not the same as carrying the character’s moral weight.
His career stretched far beyond Cybertron
Cullen became one of animation’s most dependable voices during the 1980s and 1990s. His credits included Monterey Jack in Chip ’n Dale: Rescue Rangers and characters in programmes such as Snorks, Rainbow Brite and BraveStarr.
Beginning in 1988, he also voiced Eeyore in numerous Disney films, television series and specials based on Winnie the Pooh. The gloomy donkey required a different kind of low register from Optimus Prime, although both characters benefited from Cullen’s ability to make a pause do an unreasonable amount of work.
For the 1987 science-fiction action film Predator, Cullen provided the creature’s uncredited vocal effects. His contribution helped define another enduring screen character, though one considerably less interested in compassion, integrity or community service.
In 1997, Cullen became closely associated with Toonami through narration and promotional voiceovers. He was not the block’s on-screen robotic host, TOM, despite some accounts blending the roles. Cullen was the original announcer whose voice gave the programming block much of its imposing atmosphere until its first run ended in 2008.
His later work included voicing Optimus Prime for Fortnite and an appearance connected to The Masked Singer. His most recent prominent role was Thaedus in the animated superhero series Invincible.
A performance built on compassionate strength
Hasbro inducted Cullen into the Transformers Hall of Fame in 2010. In 2023, the National Academy of Television Arts & Sciences honoured him with a Children’s & Family Emmy lifetime-achievement award.
At Hasbro’s 40th-anniversary celebration for Transformers, Cullen reflected on the franchise’s extraordinary durability. “I’ve always had the feeling this was going to go a long time,” he said. Four decades, seven live-action films and a small mountain of associated media later, this proved to be a fairly safe assessment.
His larger influence, however, came from the kind of hero he created. Optimus Prime represented masculinity without cruelty and leadership without constant self-promotion. Cullen’s delivery made patience sound powerful rather than passive. For generations of children, that message arrived from a red-and-blue alien truck, because popular culture rarely chooses the most straightforward delivery system.
Cullen’s family asked fans to honour his legacy by serving their communities and leading others with “compassion, integrity, and loyalty.” They closed with the advice that had guided his most famous performance: “be strong enough to be gentle.”
That line now stands as both a description of Optimus Prime and a concise account of what Cullen brought to him.
