Ashton Kutcher Pictures: Late Show with David Letterman 2011 Sightings Photos, Pics

Ashton Kutcher Pictures: Ashton Kutcher visits the "Late Show with David Letterman" at the Ed Sullivan Theater on August 24, 2011 in New York City.

This year, David Letterman marked his 27th year in late-night comedy and 16th year as the host of the "Late Show with David Letterman" on CBS. After more than 5,000 late-night broadcasts, he remains one of the most influential personalities in the history of television. Other than the late Johnny Carson, who hosted "The Tonight Show" for 30 years, no late-night host comes near Letterman in longevity, critical praise and award recognition. Often imitated but never matched, Letterman presents, night after night, an unpredictable hour of innovative comedy.

Photo credit: Janet Mayer / PR Photos