Darren Criss cast as Music Meister in Supergirl/The Flash musical episode TVLine brings word that the musical menace, Music Meister, has been cast for the upcoming musical episode of Supergirl and The Flash with Darren Criss set to star in the role. Criss reunites with star Grant Gustin for the episode, both having appeared as characters in the same a cappella group on Glee. “With our Flash and our Supergirl being Glee alums, how could we not have them go up against another Glee favorite like Darren Criss?” executive producer Andrew Kreisberg said.