In addition to being a superhero musical, the upcoming crossover episode betweenThe FlashandSupergirlwill be a three-wayGleereunion:Darren Crisshas been cast as the villain Music Meister.

BeforeGrant Gustinbecame the scarlet speedster, he played Sebastian Smythe, a villain of sorts and member of the a cappella group the Warblers vying for the affection of Blaine (Criss). BeforeMelissa Benoistbecame the woman of steel, she played Marley Rose. Her duet performance of “Holding Out for a Hero” while wearing a superhero outfit even predicted her upcoming casting in theArrow-verse:

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Gustin spoke about possibly bringing Criss into theFlashfold during a 2015 interview withEntertainment Tonight, saying, “I’m like, ‘Dude, we gotta get you on this thing.’ I don’t know in what capacity, but he’s got to.” Now it’s official.

According toTVLine, Criss, Gustin, and Benoist will all sing in the episode, along withCarlos Valdes(Cisco),Jesse L. Martin(Joe),Victor Garber(Dr. Stein),John Barrowman(Malcolm Merlyn), andJeremy Jordan(Winn), most of who have Broadway experience. The crossover will begin towards the end ofSupergirlon Monday, March 20th, but most of the musical action with be saved for the “Duet” episode ofThe Flashon Tuesday, March 21st.Dermott Downswill direct, and the producers of both shows have said the episodeswill come at a “pivotal” momentfor each.

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Music Meister was voiced byNeil Patrick Harrison the animated seriesBatman: The Brave and the Bold, where he used his ability to control minds through music to cause mayhem. Executive producerAndrew Kreisbergsaid of Criss’ casting:

With our Flash and our Supergirl beingGleealums, how could we not have them go up against another Glee favorite like Darren Criss? We have been blown away by his talent over the years and we can’t wait to see what he brings to the Music Meister.

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