"Invincible" creator Robert Kirkman revealed on the Escape Pod podcast that J.K. Simmons was initially considered for a different role in the series. The actor was offered the role of Cecil, head of the Global Defense Agency, but he chose another part.
According to Kirkman, the team sent Simmons the script with this offer, but he replied that he would like to play Omni-Man. The studio agreed, and the actor ultimately got the role of Nolan Grayson.
The role of Cecil eventually went to Walton Goggins. Simmons himself stated back in 2024 that he initially declined to participate in "Invincible" but changed his mind when he was offered the role of Omni-Man.