'Glee' books Helen Mirren ... or at least her voice

Helen Mirren is not high on the list of people we'd expect to find on "Glee," but, in fact, Helen Mirren will be on "Glee" in January.

More or less, anyway. TVLine reports the Oscar and Emmy winner has done some voice-over work for the episode scheduled for Jan. 17 but won't actually appear on screen.

Here's the deal: The show wrote the voice-only role with Mirren in mind -- she'll provide the "inner voice" of one of the characters, whose identity is being kept secret for now. Producers then sent regular "Glee" director Eric Stoltz, a friend who co-starred with Mirren in "The Passion of Ayn Rand" a few years ago, to approach Mirren about the role.

She said yes, and earlier this month she recorded "several long and hilarious monologues" for the character -- we're going to guess Brittany (Heather Morris) -- and visited the cast. "They had no idea she was coming," a source tells TVLine. "They were stunned."

Thoughts on Mirren doing voice work for "Glee"? Which character do you think has her "inner voice"?