Voice cast has been revealed.
https://www.comicbookmovie.com/tv/amazon/invincible-voice-cast-features-steven-yuen-jk-simmons-mark-hamill-seth-rogen-zazie-beetz-more-a176922#gs.al57s3Steven Yeun (The Walking Dead) as Mark Grayson/Invincible
J. K. Simmons (Spider-Man) as Nolan Grayson/Omni-Man
Sandra Oh (Killing Eve) as Debbie Grayson
Mark Hamill (Star Wars) as Art Rosebaum
Seth Rogen (An American Pickle) as Allen the Alien
Gillian Jacobs (Community) as Samantha Eve Wilkins/Atom Eve
Andrew Rannells (Black Monday) as William Clockwell
Zazie Beetz (Deadpool 2) as Amber Bennett
Walton Goggins (Vice Principals) as Cecil Stedman
Jason Mantzoukas (Brooklyn Nine-Nine) as Rex Sloan/Rex Splode
Chris Diamantopoulos (Silicon Valley) as Donald Ferguson, Doc Seismic
Khary Payton (Young Justice) as Black Samson
Zachary Quinto (Star Trek Beyond) as Robot
Malese Jow (The Vampire Diaries) as Kate Cha/Dupli-Kate
Kevin Michael Richardson (The Batman) as Mauler Twins, Monster Girl
Grey Griffin (Scooby-Doo) as Shrinking Ray, Amanda
Mae Whitman (Arrested Development) in an undisclosed role
Max Burkholder (Parenthood) in an undisclosed role