Hollywood has responded with a show of force on social media to the news this week that David Letterman is retiring, and among those sounding off are not only Dave's competitors but also some of his potential replacements.

"There was no pretense with David Letterman, and the response to his retirement has been just as honest," CNN reports. "From President Obama to Dave's late-night peers, the veteran host of CBS's 'Late Show' has left his fans devastated with his announcement that he plans to hang it up in 2015."

Obama reportedly posted a photo of himself with Letterman on Twitter, along with the message: "There are more than 10 reasons #DavidLetterman will be missed."

The report cites a number of other posts, including these:

Jimmy Kimmel: "David @Letterman is the best there is and ever was."

Arsenio Hall: "There's a tear under the CBS eye! David Letterman – Simply The Best!!!"

Ellen DeGeneres: "It's been 31 incredible years. Television won't be the same without you, Dave."

The report notes that Letterman said on his show Thursday night: "We don't have the timing of this precisely down, but sometime in the near distant future, 2015, for the love of God, Paul and I will be wrapping things up and taking a hike."

Seth Meyers commented during his NBC late-night show, saying: "I grew up on David Letterman. I was a little too young for [Johnny] Carson; I discovered Carson in later years online and watching videos that way. But Letterman for me was a show that you had a cool uncle, or one of your friends had a cool older brother that told you to watch. … If it wasn't for David Letterman, this show wouldn't exist. If it wasn't for David Letterman, I wouldn't be here."

Albert Brooks quipped on Twitter: "David Letterman announces that he will retire next year. CBS frantically looking for someone named Jimmy."

Judd Apatow tweeted: "@Letterman There is no way to count the amount of hours of joy and inspiration you have given me. I have watched since AM show. Thank U!"

Keith Olbermann chimed in: "@Letterman There is no way to count the amount of hours of joy and inspiration you have given me. I have watched since AM show. Thank U!"

"Seinfeld" alum Jason Alexander offered this tweet: "Mr. Letterman, you have always been the best. I've had more fun on your show and you've been a class guy all the way. Enjoy ur final days."

Noting that the conversation has turned to who might replace Letterman, CNN notes: "CBS, presumably, will have to find someone to take on Jimmy Fallon and NBC's 'Tonight Show' at 11:30. One obvious option would be to bump CBS's 'Late Late Show' host Craig Ferguson up an hour, and mimic what NBC's done with the handoff of 'The Tonight Show.'

"There's also interesting competition for Letterman's seat on cable, where Stephen Colbert and Jon Stewart have proven that they can draw a young audience and hold it. And now that Chelsea Handler is reportedly ending her E! late-night talk show, 'Chelsea Lately,' hers is another name floating amid the speculation, along with those of other funny ladies like Ellen DeGeneres and Amy Poehler."

Other names that have been mentioned, the report notes, include Louis C.K., Jerry Seinfeld and Neil Patrick Harris.

"Lena Dunham, for one, is rooting for CBS to be the network that breaks up late-night's boys club," the report adds, noting that Dunham tweeted: "I love Letterman but I am really excited about what this could mean for the diversification of late night." She added that she will "obvi … miss Letterman and his gorgeous tooth scenario/general brilliance."

Amy Poehler