Like the 1947 film starring Danny Kaye, this version is based on the 1939 short story by James Thurber.  Stiller stars as Mitty, a feckless and shy menial magazine employee who is the heroic and dashing figure in his rich imagination that he cannot be in real life.  As you might expect, though, circumstances in the world force Mitty to become more like his fantasy counterpart.

Mitty won't be in old man mode for the whole movie, but take a look at the elderly Stiller in these images from CeleBuzz and The Blemish.

Past directors who've been attached or at least interested in a new take on The Secret Life of Walter Mitty have included Ron Howard, Gore Verbinski, and the man himself, Steven Spielberg.  Mike Meyers, Jim Carrey, Will Ferrell, Sacha Baron Cohen, and Owen Wilson, meanwhile,  have been amongst the would-be Walter Mittys.

Stiller, whose previous credits as a director include Zoolander, Tropic Thunder, and The Cable Guy, which some people are finally, inevitably coming around to.  He's working from a screenplay by Steve Conrad, whose credits include The Weather Man and The Pursuit of Happyness.

The director leads the cast as Mitty, with Wiig as the second lead.  Supporting players include proven funny people like Patton Oswalt and Parks and Recreation actors Adam Scott and Kathryn Hahn, along with Josh Charles, the man who brought Dan Rydell to vivid and perfect life on Sports Night many moons ago.  Sean Penn was said to be in talks for a small but important role back in April, but we don't know for sure if that panned out.

We'll find out when The Secret Life of Walter Mitty hits theaters on December 25, 2013.