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In episode 6 of Season 1, the drunk jock that D.A. Sinclair kidnaps is voiced by Justin Roiland, the co-creator and voice of Rick Sanchez himself. It's an easy one to miss since the character barely appears, but the voice is unmistakable once you know to listen for it.
Phil Lamarr, who plays Lucan in the main cast, also lends his voice to a villain called The Walking Dread, a hulking, zombie-faced brute who can absorb energy. The name is a not-so-subtle tip of the hat to Kirkman's other big franchise, and Lamarr voicing both just makes the joke land harder.
When Emperor Argall finally shows up and speaks in Season 4, the voice belongs to Frank Welker, best known as the original voice of Megatron in the 1980s Transformers cartoon. Having him face off against Peter Cullen's Thaedus, the show's Optimus Prime, is a deliberate bit of stunt casting that Transformers fans clocked instantly.
When Invincible crossed into other comic universes during the Angstrom Levy arc, director Dan Duncan pushed to cast Josh Keaton as the Spider-Man stand-in, since Keaton had voiced Spidey in The Spectacular Spider-Man and later Across the Spider-Verse. Getting the design past Amazon's lawyers took some back and forth, apparently mostly arguments over what colour the costume was allowed to be.
It's not just Steven Yeun. Several other actors from The Walking Dead turn up across the show's voice cast, which makes sense given Kirkman created both properties. It's become something of a running theme for eagle-eyed fans to spot who's crossed over from Woodbury or Alexandria into Mark Grayson's world.
Season 4 brought in Danai Gurira to voice the villain Universa, arriving almost exactly a year after fellow Walking Dead alum Jeffrey Dean Morgan had his own turn in the series. Kirkman clearly isn't shy about pulling from his old cast list when a role fits.
John Paesano handles the score for Invincible, and outside the show he's the guy behind the music for the Maze Runner film trilogy and Marvel's Daredevil series, along with several Spider-Man video games. His work on Invincible earned its own soundtrack release, split across volumes covering the different seasons.
Not long after the Season 2 trailer dropped, Amazon quietly released a separate Atom Eve special dedicated to fleshing out Samantha Eve Wilkins' backstory before she became a bigger part of the main storyline. It's an easy one to overlook if you're only tracking numbered episodes.
By the numbers, Season 3 turned out to be the most-watched animated season Prime Video has ever put out, and the biggest returning season across every adult animation title on the platform. Not bad for a show that started out as a mid-budget adaptation of a mid-2000s indie comic.
The show landed consecutive Primetime Emmy nominations in both 2024 and 2025, and Season 3 was also nominated for the Critics' Choice Award for Best Animated Series in 2025, cementing it as one of the more critically respected superhero shows on TV right now, animated or otherwise.
