"A Katy or a Gaga" is the fourth episode of the fifth season of the American musical television series Glee, and the ninety-second episode overall. It was written by executive producers Russel Friend & Garrett Lerner, and directed by co-creator Ian Brennan, and it aired on Fox in the United States on November 7, 2013. The episode features the music of Katy Perry and Lady Gaga, the debut of guest star Adam Lambert as Elliott "Starchild" Gilbert, and the return of special guest star Demi Lovato as Dani, Santana's (Naya Rivera) girlfriend.