According to Huffington Post on Dec. 10, Stephen Colbert appeared on "The Late Show with David Letterman" in costume and pulled back his mustache to reveal that he is in "The Hobbit: The Desolation of Smaug". Colbert mentioned jokingly that this was his "breakout" role in the film and he couldn't really say where specifically he was among the crowd of citizens in Lake Town.
"I and my wife and my two boys were invited down to New Zealand to play around with the folks in 'The Hobbit' by Peter Jackson," he said. "We went down there, and we're in a scene in Laketown. I don't want to say where in the movie. It's kind of a 'Where's Waldo?'"
A known fact about Colbert is that he has vast knowledge of Middle Earth lore and has even schooled James Franco about even the most obscure characters that appeared in J.R.R. Tolkien's "Silmarillion" book. He even had a rather descriptive fan question when given the opportunity to talk to Peter Jackson about the specifics of a certain race of elves using a map and other visual aids in a video conference.