The Perfect Transformers Original Series Reunion Just Happened on Invincible

If you ever spent your childhood arguing which Transformer would win in a fight, you already know: Peter Cullen and Frank Welker are the iconic voices behind Optimus Prime and Megatron. After a long hiatus, these two legends are back swapping punches—sort of—in Amazon's gory, clever superhero series Invincible. If you like a little nostalgia sprinkled into your animated intergalactic mayhem, you’ll want to pay attention to this.

Passing the Energon Cube: Cullen and Welker’s Reunion

First, some background. The Transformers franchise is one of those rare sci-fi juggernauts that survives every reboot, every tonal shift, and several Michael Bay explosions. The constants? Peter Cullen lending those gravitas-heavy pipes to Optimus, always making lines like 'Autobots, roll out' sound cooler than they have any right to. Frank Welker, meanwhile, doesn’t just do villainous—he defines it as Megatron, but he’s also played half the Decepticon roster for fun.

Despite riding the Transformers money train in animated shows and Bay’s movie series, Cullen and Welker haven’t actually worked together on a major project since 2017. (Last time was in Transformers: The Last Knight and the animated series Robots in Disguise—not exactly classics, but at least the voices were top-notch.)

Autobot, Decepticon... Viltrumite?

If you missed it last season, Cullen stepped into Invincible as Thaedus: essentially the cosmic leader of the Coalition of Planets. Think: a wise, battle-weathered space hero with a mountain of baggage—the twist being he’s a Viltrumite (that’s the show’s answer to Kryptonians, except with even bigger daddy issues). His not-so-great claim to fame? Being labeled 'The Betrayer' for switching sides against his brutal, conquering species.

Season 4 (spoilers ahead if you’re behind) is deep in the Viltrumite War storyline. And just as we reach the boiling point, in the penultimate episode, we get a game-changing backstory reveal: enter Emperor Argall, the original Viltrum Empire boss. This guy is the template for every imperial warlord—and he’s voiced by none other than Frank Welker. Subtle? Not really, but points for giving fans what they want.

Cullen vs. Welker: A Rivalry for the Ages

The real fun here is how Invincible flips the dynamic. Cullen’s Thaedus, once again, has a major beef with Welker’s Argall—in fact, Thaedus literally kills Argall, cementing his reputation as the original rebel. In one punchy episode, the show checks a lot of boxes:

• Lets Welker bring his villain energy to a brand new role, even if it’s only for a brief yet pivotal appearance
• Sets up a new leg of the Cullen/Welker animosity—a tradition dating all the way back to Saturday morning cartoons
• Explains why Thaedus is such a complicated, haunted figure, especially for those who like their heroes morally messy

For long-time fans, catching those two voices trading blows in a completely different context is a blast. Or, as one very on-the-nose line spells out:

'The history between us does not excuse your actions, Thaedus.'

Yes, it’s a little meta. Yes, it’s absolutely what you came for.

Will There Be More?

As with all things Invincible, there’s no guarantee we’ll see Cullen and Welker share the screen again—animated or otherwise. But after nearly a decade, Prime Video just tossed Transformers fans a perfect little reunion cameo. Sometimes, fan service hits just right.