Robert Kirkman, creator of the comic book Invincible, has changed the gender of his protagonist, Tech Jacket, to Zoe, played by Zoey Deutch. This move reflects Kirkman's desire to correct a perceived lack of diversity in the cast. The decision was made due to the testosterone-fueled younger characters already appearing in the book. The fourth season of the show also featured a Hell-themed episode and a Korean-inspired episode.