The Latino actor's character is a renowned hit man in the comic franchise, who comes to Gotham to serve destruction in the most artistic of ways, and his debut will take place on Episode 9 of the sophomore season.
Castillo previously played Richie on the two seasons of HBO's Looking. He'll return for the upcoming movie special to wrap up any loose ends. He's also set to star in the Netflix original movie Special Correspondents, written and directed by Ricky Gervais.
In an interview with Out last year when Looking premiered, Castillo spoke about his transition from indie New York theater to TV:
"It's very new and this is just the first couple of weeks, so I feel like it's going to come in stages, and I'm going to see it in different ways. But so far, nothing crazy has happened. But it's great that I get to share my work with family in Texas and all my friends, with everyone who's been supportive of me, even from a distance. Now they get to see me on this kind of platform and everyone is really encouraging and excited about the show.”
Castillo also described why it was important for him to take on a gay role on Looking, despite being straight, and he said he had no fear taking on a queer role:
"I know I said this already, but once I saw Weekend, I wanted to work with Andrew. And I've played gay characters before and never had a problem with it. But I did think about how my parents would react. They're old-school Mexican. But for being old-school and traditional, they're actually very open-minded. They're so excited about the show, and they're very proud and they have been super supportive of me from day one. They're happy to see me doing what I love and they're relieved that I'm now able to make a living doing it.”
Gotham's second season premiered September 21.