Fox's Gotham series could not fully transform its villain Jerome Valeska into the Joker. Warner Bros. restricted key elements to preserve the character for its films.
Cameron Monaghan, who played twins Jerome and Jeremiah Valeska on the show, revealed the restrictions in a 2018 social media post. Pure green hair and the name Joker were off limits due to a decision from high up at Warner Bros. The studio was developing its 2019 Joker movie at the time and sought to avoid diluting the brand. Monaghan wrote that the limits allowed creativity on the TV side while respecting the lucrative film potential. In the series finale, Jeremiah Valeska adopted a closer Joker appearance with pale skin and a purple outfit after Jerome's death in season 4. Monaghan told TV Insider that the final season brought more leniency thanks to fan demand and the cast pushing back.