With the genre's elder statesman planning to sign off in 2015, celebrities of all stripes weighed in on the latest upheaval in late night.
Here are a few of the most notable reactions:
Fellow gabber Andy Cohen: "Letterman broke the mold for not just Late Night, but TV itself. He's a vanguard- his influence is seen all over the dial today. What a run!"
Reality star Donald Trump: "I can't believe David Letterman has announced his retirement--he is a great guy!"
Late-night rival Arsenio Hall: There's a tear under the CBS eye! David Letterman - Simply The Best!!!