When Barry Allen and Kara Danvers reunite for "The Flash"/"Supergirl" musical crossover, they'll face a foe familiar to viewers of the animated "Batman: The Brave and the Bold."

RELATED: The CW Renews “Arrow,” “Flash,” “Supergirl” and “Legends of Tomorrow”

During The CW's presentation at the Television Critics Association winter press tour, executive producer Greg Berlanti confirmed the villain will indeed be the Music Meister, who can control people through song. But before you get excited about the prospect of Neil Patrick Harris reprising his animated role in live-action, Berlanti cautions that the process hasn't gotten that far.

"We haven't gone about casting yet. It's the right question though!" he was quoted as saying by IGN.com.

Harris addressed rumors last month that he could return to the role for the crossover, saying, "I’ve heard about it, but that’s as much as it has been. I mean, I did the Music Meister in a recording booth in L.A. … 15 years ago or something, y’know, and it comes out a year later. […] It was a fun episode, it was a good thing to day. But I’ve heard that Joss [Whedon] is involved in some way, but I don’t know if that’s true or not. … He wears a big zoot suit, from what I remember. The song was fun to sing, so I don’t know; we’ll see.”

RELATED: Matt Ryan Returns as Constantine in New Animated Series

Harris, who starred in Whedon’s 2008 musical “Dr. Horrible’s Sing-Along Blog” and, later, in the Broadway production of “Hedwig and the Angry Inch,” appeared as the Music Meister on “Batman: The Brave and the Bold’s” 2009 episode “Mayhem of the Music Meister!” In the acclaimed musical episode, the villain could control others — including Batman, Green Arrow, Black Canary, Aquaman, Gorilla Grodd and Black Manta — through song.

No date has been announced for "The Flash"/"Supergirl" crossover, starring Grant Gustin and Melissa Benoist, both veterans of Fox's musical comedy-drama "Glee."