While we knew for a while there was likely going to be a Supergirl/Flash musical crossover, we now know who the villain is in the episode.

Joining his former Glee classmates will be actor Darren Criss, who has been cast as the Music Meister, TVLine reported.

Criss played alongside Grant Gustin and Melissa Benoist on Glee even though Gustin and Benoist themselves did not appear onscreen together until their respective shows.

Executive producer Andrew Kreisberg stated, “how could we not have them go up against another Glee favorite like Darren Criss?”

He said they were also looking forward to what he could bring to the role. The crossover is set to begin at the end of Supergirl on March 20 while The Flash will continue the action on March 21.

Other stars singing in the musical crossover include Jesse L. Martin, Victor Garber, Carlos Valdez, John Barrowman and Jeremy Jordan.

Criss tweeted about the news ending it with “Music to my ears!”

Supergirl returns from winter hiatus Jan. 23 while The Flash returns on Jan. 24 on the CW.