Glee has been reaching for a handful of pretty big name guest stars lately. Ricky Martin, Gloria Estefan, Pitbull, Chewbacca... but this one tops the lot of them: Helen Mirren—the Helen Mirren—will contribute her talents to Fox's musical series. But here's the catch: Mirren will not exactly be appearing on Glee. Instead, she'll be providing her voice alone to the show. Mirren's "character" will be the inner voice to one of Glee's regulars.
Whether this is along the lines of a helpful Jiminy Cricket conscience or a demonic The Shining homage is yet to be seen, as is which character will be aided/tortured by Mirren's presence in his or her mind. But if I had to guess, I'd say the breakout basket case that is Brittany Pierce (Heather Morris) will be the character injected with this classy dose of internal narration.
According to recurring Glee director Eric Stoltz, his friend/former collaborator Mirren was an easy sell for the role: she is a big fan of the show, and was more than willing to lend her voice for the part.