Kirkman also revealed more details about the stacked cast, which already includes Zazie Beetz as Amber Bennet Chris Diamantopolous as Doc Seismic, Walton Goggins as Cecil Steadman, Grey Griffin as Shrinking Rae & Amanda (Monster Girl as Girl), Mark Hamill as Art, Gillian Jacobs as Atom Eve, Melise as Dulpi-Kate, Jason Mantzoukas as Rex Splode, Andrew Rannells as William Clockwell, Kevin Michael Richardson as Mauler 1, Mauler 2 & Monster Girl (as Monster) and Seth Rogen as Allen the Alien.
Steven Yuen was previously reported to be playing Mark Grayson with J.K. Simmons and Sandra Oh reportedly being tapped to voice his parents.