Actors, comics and musicians have been taking to Twitter, Instagram and Facebook to share their congratulations and memories from their time on Letterman's show.
Some even shared stories of how the 68-year-old TV personality influenced their lives and careers. For example, Parks and Recreation star Adam Scott tweeted: "A good 80% of why I wanted to do any of this was to one day sit on Letterman's couch."
A good 80% of why I wanted to do any of this was to one day sit on Letterman's couch.— Adam Scott (@mradamscott) May 20, 2015
In the summer of 85 I discovered Late Night with David Letterman by accident and it blew my 12 yr old mind.— Adam Scott (@mradamscott) May 20, 2015
Without fail I watched every night & felt like I was the only person in the world still awake, that this insane show was made just for me.— Adam Scott (@mradamscott) May 20, 2015
It changed the way I thought about TV, defined what I found funny, and helped shape how I look at the world— Adam Scott (@mradamscott) May 20, 2015
Some stars didn't want to accept the reality of the situation. Jennifer Lawrence posted a photo begging Letterman not to leave.
Even his fellow late-night hosts encouraged their viewers not to miss his last episode.
Many celebrities just wanted to make it known that they appreciated all the laughs and good times from Letterman's long, groundbreaking career in late-night television.
This is a contrarian opinion but I love old Letterman more than young Letterman— B.J. Novak (@bjnovak) May 20, 2015
If Andy Kaufman's still alive, the final David Letterman show would be the time & place to reveal it.— Patton Oswalt (@pattonoswalt) May 20, 2015
Watching last eps of Letterman - always a fan, never a guest- wish him the best. Btw Stephen Colbert @StephenAtHome you're a handsome man.— John Stamos (@JohnStamos) May 20, 2015
20 years ago my first TV show was @Letterman. He has been my favorite since I was a kid. Every time was a thrill. Thanx, Dave.— Rob Thomas (@ThisIsRobThomas) May 20, 2015
Thank you @letterman for allowing odd comedians like me to go into pitch mtgs & say "But look what Letterman did in the 80s! And it worked!"— billy eichner (@billyeichner) May 20, 2015
Congratulations to David Letterman, who I now believe is beginning his third career in show business.— Steve Martin (@SteveMartinToGo) May 20, 2015
This truly is the end of an era, and it will be interesting to see how his successor, Stephen Colbert, does behind the Late Show desk.