Cal Kestis was modeled after his voice actor, Cameron Monaghan. Monaghan has appeared in countless movies and television shows since he made his acting debut in The Wishing Stone in 2002, the actor is perhaps best known for his role in Shameless as Ian Gallagher, and his turn as twin brothers Jerome and Jeremiah Valeska in Gotham – who serve as the origins for The Joker.